SAT Math Multiple Choice Practice Question 415: Answer and Explanation

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Question: 415

19.

What is the area of square ABCD ?

A. 25
B. 18
C. 26
D. 25 +
E. 36

Correct Answer: C

Explanation:

C First a little error avoidance: Because 5 is one of the numbers you see, 52, or 25, is not going to be the answer. It's a Joe Bloggs answer. So, eliminate A. Next, let's estimate the area before you try to solve directly. The length of the square's side is a little more than 5, so the area is going to be a little more than 52, or 25. E is too large, so before solving the problem, you've eliminated A and E. If you couldn't calculate the area exactly, you could guess from among the remaining choices. To determine the area, let's begin by assigning the variable s to indicate the length of the square's sides. The area is given by this formula: A = s2. Notice the triangle formed by side and the x- and y-axes. The base of that triangle is 1 and the height is 5, so you can use the Pythagorean theorem to find the length of side or s:

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