Use the image to answer the question.

A composite shape is drawn using a rectangle and a triangle. The rectangle has a base labeled as 6 centimeters. A triangle showing a perpendicular height of 6 centimeters is stacked on the top side of the rectangle. The base of the triangle and the top of the rectangle have a common side. Right angle symbols are shown on all four corners of the rectangle.

John Roy creates this drawing of a composite shape for an art contest. The area of the drawing is 78 square centimeters. What is the height of the rectangle?

(1 point)
Responses

10 centimeters
10 centimeters

8 centimeters
8 centimeters

13 centimeters
13 centimeters

12 centimeters
12 centimeters
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1 answer

The height of the rectangle can be calculated by dividing the total area of the composite shape by the base of the rectangle and the height of the triangle:

Area = base x height / 2 + base x height

78 = 6 x h / 2 + 6 x h
78 = 3h + 6h
78 = 9h
h = 78 / 9
h = 8.67 cm

Therefore, the height of the rectangle is approximately 8.67 cm, which is closest to 8 centimeters.