Answer: 20 square units (choice C)
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Explanation:
Ignore the portions that are 12 and 13 units long.
The base of triangle ABC is 8 units long. The height is 5 units. The base and height are always perpendicular.
The area is base*height/2 = 8*5/2 = 40/2 = 20 square units
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Side note:
You could find the area of triangle ABD, where D is at the 90 degree angle location, and then subtract off the area of triangle ACD. This is a slightly longer approach compared to the first section above.
