Can someone help me find what I did wrong?

Code:
#pragma once


namespace RightTriangleSolver {


    using namespace System;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Windows::Forms;
    using namespace System::Data;
    using namespace System::Drawing;


    /// <summary>
    /// Summary for Form1
    /// </summary>
    public ref class Form1 : public System::Windows::Forms::Form
    {
    public:
        Form1(void)
        {
            InitializeComponent();
            //
            //TODO: Add the constructor code here
            //
        }


    protected:
        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        ~Form1()
        {
            if (components)
            {
                delete components;
            }
        }


    protected: 




























    private: System::Windows::Forms::Label^ label4;
    private: System::Windows::Forms::Label^ label1;
    private: System::Windows::Forms::Label^ label2;
    private: System::Windows::Forms::Label^ label3;




    private: System::Windows::Forms::Button^ button3;
    private: System::Windows::Forms::TextBox^ num1;
    private: System::Windows::Forms::TextBox^ num2;
    private: System::Windows::Forms::TextBox^ c;




































    private: System::ComponentModel::IContainer^ components;


    protected: 


    private:
        /// <summary>
        /// Required designer variable.
        /// </summary>




#pragma region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        void InitializeComponent(void)
        {
            this->label4 = (gcnew System::Windows::Forms::Label());
            this->label1 = (gcnew System::Windows::Forms::Label());
            this->label2 = (gcnew System::Windows::Forms::Label());
            this->label3 = (gcnew System::Windows::Forms::Label());
            this->button3 = (gcnew System::Windows::Forms::Button());
            this->num1 = (gcnew System::Windows::Forms::TextBox());
            this->num2 = (gcnew System::Windows::Forms::TextBox());
            this->c = (gcnew System::Windows::Forms::TextBox());
            this->SuspendLayout();
            // 
            // label4
            // 
            this->label4->AutoSize = true;
            this->label4->Font = (gcnew System::Drawing::Font(L"Segoe Print", 26.25F, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
                static_cast<System::Byte>(0)));
            this->label4->ForeColor = System::Drawing::Color::Red;
            this->label4->Location = System::Drawing::Point(44, 9);
            this->label4->Name = L"label4";
            this->label4->Size = System::Drawing::Size(400, 61);
            this->label4->TabIndex = 8;
            this->label4->Text = L"Right Triangle Solver";
            // 
            // label1
            // 
            this->label1->AutoSize = true;
            this->label1->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 20.25F, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
                static_cast<System::Byte>(0)));
            this->label1->Location = System::Drawing::Point(51, 109);
            this->label1->Name = L"label1";
            this->label1->Size = System::Drawing::Size(32, 31);
            this->label1->TabIndex = 9;
            this->label1->Text = L"A";
            // 
            // label2
            // 
            this->label2->AutoSize = true;
            this->label2->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 20.25F, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
                static_cast<System::Byte>(0)));
            this->label2->Location = System::Drawing::Point(51, 164);
            this->label2->Name = L"label2";
            this->label2->Size = System::Drawing::Size(32, 31);
            this->label2->TabIndex = 10;
            this->label2->Text = L"B";
            // 
            // label3
            // 
            this->label3->AutoSize = true;
            this->label3->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 20.25F, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
                static_cast<System::Byte>(0)));
            this->label3->Location = System::Drawing::Point(49, 221);
            this->label3->Name = L"label3";
            this->label3->Size = System::Drawing::Size(34, 31);
            this->label3->TabIndex = 11;
            this->label3->Text = L"C";
            // 
            // button3
            // 
            this->button3->Font = (gcnew System::Drawing::Font(L"Microsoft Sans Serif", 12, System::Drawing::FontStyle::Regular, System::Drawing::GraphicsUnit::Point, 
                static_cast<System::Byte>(0)));
            this->button3->Location = System::Drawing::Point(193, 265);
            this->button3->Name = L"button3";
            this->button3->Size = System::Drawing::Size(113, 30);
            this->button3->TabIndex = 14;
            this->button3->Text = L"Solve for C!";
            this->button3->UseVisualStyleBackColor = true;
            this->button3->Click += gcnew System::EventHandler(this, &Form1::button3_Click);
            // 
            // num1
            // 
            this->num1->Location = System::Drawing::Point(165, 106);
            this->num1->Name = L"num1";
            this->num1->Size = System::Drawing::Size(169, 20);
            this->num1->TabIndex = 15;
            // 
            // num2
            // 
            this->num2->Location = System::Drawing::Point(165, 163);
            this->num2->Name = L"num2";
            this->num2->Size = System::Drawing::Size(169, 20);
            this->num2->TabIndex = 16;
            // 
            // c
            // 
            this->c->Location = System::Drawing::Point(165, 221);
            this->c->Name = L"c";
            this->c->Size = System::Drawing::Size(169, 20);
            this->c->TabIndex = 17;
            // 
            // Form1
            // 
            this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->ClientSize = System::Drawing::Size(471, 307);
            this->Controls->Add(this->c);
            this->Controls->Add(this->num2);
            this->Controls->Add(this->num1);
            this->Controls->Add(this->button3);
            this->Controls->Add(this->label3);
            this->Controls->Add(this->label2);
            this->Controls->Add(this->label1);
            this->Controls->Add(this->label4);
            this->Name = L"Form1";
            this->Text = L"Form1";
            this->ResumeLayout(false);
            this->PerformLayout();


        }
#pragma endregion
    private: System::Void pictureBox1_Click(System::Object^ sender, System::EventArgs^ e) {
             }
    private: System::Void button2_Click(System::Object^ sender, System::EventArgs^ e) {
             }
private: System::Void pictureBox1_Click_1(System::Object^ sender, System::EventArgs^ e) {
         }
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
         }
private: System::Void button3_Click(System::Object^ sender, System::EventArgs^ e) {
             this->c = Math::Sqrt(Math::Pow(num1,2)+Math::Pow(num2,2));
         }
};
}
ERROR:1>------ Build started: Project: Right Triangle Solver, Configuration: Debug Win32 ------
1>Build started 1/22/2013 1:31:45 PM.
1>InitializeBuildStatus:
1> Touching "Debug\Right Triangle Solver.unsuccessfulbuild".
1>GenerateTargetFrameworkMonikerAttribute:
1>Skipping target "GenerateTargetFrameworkMonikerAttribute" because all output files are up-to-date with respect to the input files.
1>ClCompile:
1> All outputs are up-to-date.
1> Right Triangle Solver.cpp
1>c:\users\admin\documents\visual studio 2010\projects\right triangle solver\right triangle solver\Form1.h(215): error C2664: 'System::Math::Pow' : cannot convert parameter 1 from 'System::Windows::Forms::TextBox ^' to 'double'
1> No user-defined-conversion operator available, or
1> There is no context in which this conversion is possible
1>c:\users\admin\documents\visual studio 2010\projects\right triangle solver\right triangle solver\Form1.h(215): error C2664: 'System::Math::Pow' : cannot convert parameter 1 from 'System::Windows::Forms::TextBox ^' to 'double'
1> No user-defined-conversion operator available, or
1> There is no context in which this conversion is possible
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.77
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========