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# Using the Pythagorean Theorem: Area of an Isosceles Triangle

### See also

A video lesson where I explain how to find the area of an isosceles triangle when its sides are given — an easy application of the Pythagorean Theorem. We first calculate the altitude of the triangle using the Pythagorean Theorem and then calculate the area using the common formula for the area of a triangle (base times altitude divided by 2).

The Pythagorean Theorem - a video lesson

Using the Pythagorean Theorem 2: Diagonal of a Square - a video lesson

Using the Pythagorean Theorem 3: volume of a triangular prism - a video lesson

Using the Pythagorean Theorem 4: perimeter of a trapezoid - a video lesson

Math Mammoth Grade 7 curriculum (pre-algebra)