SAT Math Multiple Choice Practice Question 415: Answer and Explanation
What is the area of square ABCD ?
D. 25 +
Correct Answer: C
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: