Question

Determine the size of angle B in triangle ABC below:
NO LINKS!

Answer 1

x = 70 °

Explanation:

Two sides (CB & CA) of an isosceles triangle are equal.

The two angles (CBA & CAB) surrounding the third side (BA) are also equal.

• x = CBA = CAB

The interior angles of a triangle add up to 180°.

180 = 40 + x + x

180 = 40 + 2x

• Take 40 away from both sides.

140 = 2x

• Divide both sides by 2.

x = 70