Khan Academy: Triangles: Area of Diagonal Triangles of Rectangle Are Equal

A triangle, square, hexagon, and circle all have a perimeter of one unit. Eighth graders must attempt to find the area of each and arrange them in order from least to greatest areas. A terrific task for applying four different...

Need an activity for teaching the Pythagorean Theorem? Geometry juniors apply the Pythagorean theorem to two triangles to determine a final calculation. 

This lecture explores the area of each triangle created by drawing two diagonal lines through a rectangle. It provides a detailed explanation of how to use a formula to solve the given problem. Tip: Use this for test preparation purposes.

This lecture explores finding the area of each of the triangles created by drawing two diagonal lines through a rectangle. It provides a detailed explanation of how to use a formula to solve the given problem. Tip: Use this for test...

This video tutorial [4:36] shows that the four triangles created by the diagonals of a rectangle all have the same area.

The teachers uses a diagram to set up her initial equation to reflect the changes being made to a garden plot. She has a good explanation of how she got her equation. Then she works through the steps to solve the equation.

This video [7:50] demonstrates how to determine the area a regular hexagon with side length of 2 sq. rt. 3 based on knowledge of 30-60-90 triangles and the area formula of a triangle.

Trapezoids can be tricky! Break down the process of finding the area of a trapezoid with an engaging math video. Learners explore area formula and shown exactly how to plug in information, solve, and simplify. 

This video tutorial explores finding the formula for the area of an equilateral triangle with side length of s.

Students explore a problem that requires then to figure out the area of an equilateral triangle inscribed in a circle using a little trigonometry.