Final: Master of Triangles

To find the area of an isosceles triangle, first find its height with the Pythagorean theorem. The equal side is the hypotenuse and half the base is one leg. Then put that height and the whole base into the area formula, half the base times the height. Work out the squares first, then the square root, and finally the product. For example, an isosceles triangle with equal sides 5 and base 6 has height √(5^2 - 3^2) = 4 and area 1/2 × 6 × 4 = 12. Half the base, 3, goes under the root, and the whole base, 6, goes in the area formula.