The answer is 78.5 you can get this by multiplying pi by the radius which is 5 then square it and you get 78.5
In similar triangles, the ratios of corresponding sides are equal.
This means
y/6=5/(4+5)
Cross multiply
y=5*6/(4+5)=30/9=10/3 (or 3 1/3)
Multiplying both sides of an equation by the same number keeps the equation true. In this example, both sides are multiplied by 3, so the equation isn't changed.
