There are four types of triangle:

(A mark on a line means that it is the same length as another line with the same mark).

In a triangle, one angle is 30º and a second angle is 60º.

What type of triangle is it?

The two angles add up to 90º.

There are 180º in a triangle, so the remaining angle is 90º.

Answer: Right angled triangle

A triangle has sides of length `x`, `x` and `2x`.

What type of triangle is it?

Two of the sides are the same length.

Answer: Isosceles triangle.

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