SAT Math Multiple Choice Practice Question 79: Answer and Explanation
13. Find the perimeter of a square whose diagonal has length m.
A. 6 m
C. 24 m
E. 48 m
Correct Answer: C
C. Here's the square with the diagonal drawn:
Hopefully, you recognize that the triangles in this drawing are both 45-45-90 triangles. So the hypotenuse — which is also the diagonal of the square — equals a leg times . Because the legs are just the sides of the square, each leg equals 6 m, and the perimeter is 4 × 6 m = 24 m.