## What is the third side of an isosceles triangle?

base

In an isosceles triangle that has exactly two equal sides, the equal sides are called legs and the third side is called the base. The angle included by the legs is called the vertex angle and the angles that have the base as one of their sides are called the base angles. The vertex opposite the base is called the apex.

## How do you find the third side of an isosceles triangle with only 2 sides and angle known?

You will have to lookup the cosine of your base angle. then multiply the known side by the cosine of your base angle. That gives you half the base. Double it and you have the missing side.

**How do you find the unknown side of an isosceles triangle?**

To find an unknown side of a triangle, you must know the length of other two sides and/or the altitude. To find the unknown base of an isosceles triangle, using the following formula: 2 * sqrt(L^2 – A^2), where L is the length of the other two legs and A is the altitude of the triangle.

### Can you use Pythagorean theorem on an isosceles triangle?

The Pythagorean theorem can be used to solve for any side of an isosceles triangle as well, even though it is not a right triangle. Isosceles triangles have two sides of equal length and two equivalent angles. In your drawing, the 8 inch side should be at the base of the triangle.

The third side of the triangle is called base. Vertex angle is the angle between the legs and the angles with the base as one of their sides are called the base angles. Properties of the isosceles triangle:

### What are the properties of an isosceles triangle?

An isosceles triangle is a triangle with two sides of equal length, which are called legs. The third side of the triangle is called base. Vertex angle is the angle between the legs and the angles with the base as one of their sides are called the base angles. Properties of the isosceles triangle: it has an axis of symmetry along its vertex height

**How do you find the length of an isosceles triangle?**

Given the height, or altitude, of an isosceles triangle and the length of one of the legs or the base, it’s possible to calculate the length of the other sides. The base length b is equal to 2 times the square root of leg a squared minus the height h squared.

## Is △Def an isosceles or equilateral triangle?

DE≅DF≅EF, so △DEF is both an isosceles and an equilateral triangle. For an isosceles triangle with only two congruent sides, the congruent sides are called legs.