Triangles, trapeziums and mixed areas
Answers are for parents and teachers.
1
Find the area of an obtuse triangle with base 10 cm and height 6 cm (outside).
10 × 6 ÷ 2 = 30 cm².
2
Find the area of a trapezium with parallel sides 7 cm and 13 cm and height 8 cm.
(7 + 13) × 8 ÷ 2 = 80 cm².
3
A trapezium has area 54 m², parallel sides 5 m and 13 m. Find its height.
54 × 2 ÷ 18 = 6 m.
4
A parallelogram has base 16 cm and height 5 cm. A triangle has the same base and height. Find both areas.
Parallelogram: 80 cm². Triangle: 40 cm².
5
Omar says a triangle with base 6 cm and a slanted side of 7 cm and height 4 cm has area 6 × 7 ÷ 2 = 21 cm². Correct him.
He used the slanted side. The area is 6 × 4 ÷ 2 = 12 cm².