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smc

geometry senior

Problem

The figure is constructed from line segments, each of which has length . The area of pentagon can be written as , where and are positive integers. What is
problem
(A)
(B)
(C)
(D)
Solution
Draw diagonals and to split the pentagon into three parts. We can compute the area for each triangle and sum them up at the end. For triangles and , they each have area . For triangle , we can see that and . Using Pythagorean Theorem, the altitude for this triangle is , so the area is . Adding each part up, we get .
Final answer
D