Answer:
Step-by-step explanation:
The area of a circle is A = πr², where r is the radius. That means in order to solve this we have to find the value of x, which is the diameter of the lake, and then divide it in half to get the radius. To find x we will use similar triangles and proportions. x is the height of the big triangle and 4.5 is the height of the smaller triangle; 15.3 + 7.4 is the hypotenuse of the big triangle and 7.4 is the hypotenuse of the smaller triangle. Setting up our proportion:
which simplifies a bit to
and cross multiply to solve for x:
7.4x = 102.15 so
x = 13.8 That is the diameter of the lake. Divide it in half to get 6.9, the radius. Applying the area formula for a circle:
A = (3.14)(6.9)² and
A = 3.14(47.61) so
A = 149.5 which rounds to 150, Choice C