Use the image to answer the question.
An illustration shows a 5 by 9 grid labeled Triangle C. Triangle C is graphed on the grid.
Use decomposition and rearranging to model the area formula of triangle C . What is the area of triangle C in square units?(1 point)
Responses
10.5 square units
10.5 square units
10.5 cubic units
10.5 cubic units
21 square units
21 square units
10.5 units
To find the area of a triangle, you can decompose it into a rectangle and a right triangle, and then rearrange those shapes to find the area formula.
In this case, you can decompose Triangle C into a rectangle with dimensions 5 by 9 and a right triangle with dimensions 4.5 by 6. You can rearrange those shapes to form a rectangle with dimensions 9 by 9, which has an area of 81 square units.
Since the right triangle that was removed from Triangle C had an area of 9 square units, you subtract 9 from 81 to get the area of Triangle C, which is 72 square units.
Therefore, the correct answer is not provided, but the closest option is 21 square units.