Area of a parallelogram and of a triangle
Answers are for parents and teachers.
1
The sides of a parallelogram are 20 cm and 15 cm and the altitude to the 20 cm side is 6 cm. How long is the altitude to the 15 cm side (cm)?
8
2
A triangle has area 84 cm² and an altitude of 12 cm. How long is the side to which it is drawn (cm)?
14
3
Two triangles have equal bases and altitudes 4 cm and 12 cm. If the first has area 18 cm², what is the area of the second (cm²)?
54
4
The area of triangle ABC is 90 cm² and D is the midpoint of AB. What is the area of triangle ACD (cm²)?
45
5
How can the triangle area formula be proved using a parallelogram?
Complete the triangle with a congruent triangle to a parallelogram of area ah; the triangle is half of it.