In this activity, we are going to be looking at angles in special triangles!

We know that:-

We can use it to find missing angles in triangles!

**Answer**

We know that the sum of the three angles is 180^{o}

We can say that R = 180 - (25 + 96)

R = 180 - 121

**R = 59 ^{o}**

There are two special triangles for us to consider.

__1) The Equilateral Triangle__

__All__ the sides are the same length.

__All__ the angles are the same.

**2) Isosceles Triangle**

__Two__ of the sides are the same length.

__Two__ of the angles are the same

These facts help us to find missing angles in triangles.

Let's have a look at a question.

__Example__

Calculate the size of angle A in the **equilateral triangle** below.

**Answer**

As the triangle is equilateral, we know that all the angles are the __same__.

We also know that angles in a triangle add up to 180^{o}

Therefore, angle A = 180 ÷ 3 = 60^{o }

Let's try some mixed questions now!