SAT Math Multiple Choice Practice Question 425: Answer and Explanation

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Question: 425

8. D (–6, 3)

E (–1, –1)

F (–1, 3)

The coordinates of points D, E, and F in the xy-plane are given above. What is the perimeter of △DEF ?

A. 12
B. 20
C. 9 + (approximately 13.12)
D. 9 + (approximately 15.40)
E. (approximately 12.25)

Correct Answer: D

Explanation:

D Draw the missing figures. When you sketch this out, you'll see that it's a right triangle with legs of lengths 4 and 5. Use the Pythagorean theorem: 42 + 52 = c2. Now solve for c. c2 = 41 and c = . Remember that the question asked for perimeter, so add up the sides: 4 + 5 + = 9 + , which is choice D.

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