You will need

- geometric formula to find the area of an isosceles triangle ABC:
- S = 1/2 x b x h, where:
- - S - the area of the triangle ABC,
- - b - the length of its base AC,
- - h - the length of its height.

Instruction

1

Measure the length of the base AC of an isosceles

**triangle**ABC, usually the length of the base**of the triangle**is given in terms of the problem. Let the length of the base is equal to 6 cm Measure the height of an isosceles**triangle**. The height is a segment drawn from the vertex**of the triangle**perpendicular to its base. Let the conditions of the problem height h = 10 cm.2

Calculate

**area**of isosceles**triangle**formula. To do this, divide the length of the base AC in half: 6/2=3 cm, so 1/2b=3 cm. Multiply half the base length as**the triangle**on the length of the height h: 3 x 10=30 cm, you found**the area of the**isosceles**triangle**ABC the length of its base and height. If the length of the altitude is unknown, but given the length of a side**of a triangle**, then we first find the length of altitude of an isosceles**triangle**by the formula h = 1/2·√(4a2 – b2).3

Calculate the length of the height of an isosceles

**triangle**by length of sides and base. Let a be the length of any side of an isosceles**triangle**, in terms of the problem it is equal to 10 cm Substituting values of the lengths of the sides and base of an isosceles**triangle**in the formula, find the length of its height h=1/2√(4x100 – 36) =10 cm Calculate the height of an isosceles**triangle**, to continue the calculation, substituting the found values to the specified formula for finding the area**of a triangle**by its height and base.Note

In an isosceles triangle the altitude is also the median and the angle bisector of the triangle.

Two angles of an isosceles triangle are equal.

Two angles of an isosceles triangle are equal.