Question

A parallelogram is made up of a rectangle with a base of 12 centimeters (cm) and a height of 5 cm, and two triangles, each with a base of 2 cm and height of 5 cm. Jeremy calculates the area of the parallelogram by multiplying the base and height of the rectangle to get 60 cm2.

Is Jeremy's answer correct? Why or why not?

Select the option that correctly answers both questions.

No, he forgot to multiply by 12 when calculating the area of the rectangle.

Yes, he correctly calculated the area of the parallelogram as b⋅h.

No, he forgot to add the area of the triangles to the area of the rectangle.

Yes, he correctly calculated the area of the parallelogram as 12bh.

Answer 1

No, he forgot to add the area of the triangles to the area of the rectangle.

It is said that Jeremy thought he solved for the area of the whole parallelogram correctly by multiplying the base and height of the rectangle, which is just a part of the whole parallelogram.

Jeremy’s answer is incomplete, he only calculated the area of the triangle as the answer.

This is because one way of finding an area of a parallelogram is dividing the shape into a rectangle with a triangle on each side.

The real area of the parallelogram is 70 cm^2
(with areas of each triangles added)

With that being said, the formula of a parallelogram that is said is:
A = bh
Which means a height perpendicular to the base of the whole paralleogram.