Find Missing Angles in a Triangle

In this activity, we are going to be looking at angles in a triangle!

 

 

Let's take a triangle.

We can make one using a piece of A4 paper.

 

1) Cut the paper into a triangle - any type of triangle will do as long as the sides are straight!

 

2) Label the angles.

 

 

3) Tear off the corners like this!

 

 

 

4) Put the corners together like this!

 

 

It should form a half turn or straight line which is 180^o

It works for any triangle - equilateral, isosceles, right-angled or scalene

 

Good to know! Make a note of this!

 

 

We can use it to find missing angles in triangles!

 

Let's try a typical question!

 

 

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

 

Let's try some questions now!