Answer:Area of triangle is 18cm2 There is a dotted line to show us how to do,we know the dotted means we don’t actually work that part out. 1. The bottom added together = 11,now : (11x6) ÷ 2 = 33cm2. 2.The part where there is a dotted triangle: (6x5) ÷ 2 = 15cm2. 3. 33 - 15 = 18.