Question

abcd and efg are parallel lines. BC=CF. Angle BFE=70°. work out the size of angle x with reasons

Answer 1

CBF = BFE (interior angles)
CBF = CFB = 70° (isosceles triangle, BC = BF)
CBF + CFB + BCF = 180° (summation of all angles in a triangle always equals 180°)
so we have : 70° + 70° + x = 180°
so x= 40°