Official Explanation
Use the formula for the area of a circle, area = \(πr^2.\) Since the area is given as \(36π,\) we know \(πr^2 = 36π.\) Now look for cancellation! Dividing both sides by \(π\) yields \(r^2 = 36\) and \(r = 6.\) Because the radius is 6, two sides lengths of the triangle equal 6. If x were equal to 90, then the triangle would be a right triangle and its area, given by × base × height would equal × 6 × 6, or 18.
But we are given x > 90, which makes the height of the triangle less than 6 and the area less than 18, so (B) is greater. Notice that in an obtuse triangle, when the base is a side adjacent to the obtuse angle, then the altitude drawn for the purposes of computing area lies outside the triangle and is smaller than either of the other two sides.
Answer: B