geometry
posted by Piggy .
A 306090 triangle is inscribed in a circle. The length of the hypotenuse is 12 inches. If a coin is tossed on the figure, what is the probability that the coin will land in the circle, but outside the triangle?

All righttriangles inscribe in a circle with a diameter equal to the hypotenuse.
Therefore for the 306090 triangle, the radius of the circle is 6 inches, and the short side is also 6 inches. The height is 6sqrt(3), so the area of the triangle is
At=36sqrt(3)/2 = 18 sqrt(3) sq.in.
The area of the circle is
Ac=π6^2=36π
The probability of falling inside the circle and outside the triangle is therefore
P(C\T)=(AcAt)/Ac 
the quesiton is land in the circle, but outside the triangle. Is it the probability is (AC  AT)/AC
81.22/113 x 100%
= 72% 
Correct.
I get
P(C\T) (probability inside circle minus triangle)
=(AcAt)/Ac
=81.92/113.1=72.4%