Mr. morris is going to save money and replace his sailboat's mainsail himself. he must determine the area of the mainsail in order to buy the correct amount of material. calculate the area of the parallelogram to determine how much material should be purchased. be sure to explain how to decompose this shape into rectangles and triangles. describe their dimensions and show your work. parallelogram with base of 15 feet, height of 10 feet, and triangular base of 2 feet.

The problem statement describes the dimensions. The base length is 15 ft; the height is 10 ft.

The area of a parallelogram is the product of base length and height, just as it is for a rectangle.
  A = bh
  A = (15 ft)(10 ft) = 150 ft²

Mr Morris should purchase 150 ft² of material.

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If you compare the area to a 15 ft by 10 ft rectangle, you see the "excess" triangle at the left end just matches the "missing" triangle at the right end. The A=bh formula still works even if the top and base are offset by more than the width of the base.