Calculate Rectangle Area: 7-Unit Triangle and 10-Unit Height Problem

An isosceles right triangle has two equal sides (both legs = 7) and a right angle between them. The small square symbol in the diagram shows the right angle.

Look at the diagram carefully! The hypotenuse of the triangle (the slanted side) forms the top edge of the rectangle, making it the width.

The number 7 represents the legs of the triangle, not the rectangle's width. The rectangle's width is the triangle's hypotenuse, which you must calculate using the Pythagorean theorem.

The problem asks for the area, and the correct answer choice is ≈99. Calculate $\sqrt{98} \times 10 \approx 9.899 \times 10 ≈ 99$.

Remember: $a^2 + b^2 = c^2$ where a and b are the legs, and c is the hypotenuse. Here: $7^2 + 7^2 = c^2$, so $c = \sqrt{98}$.