In triangle JKL, we have JK = JL = 25 and KL = 30. Find the inradius of triangle JKL and the circumradius of triangle JKL.
Draw altitude JM. Because the triangle is isosceles, KM=ML=15.
Then, by the Pythagorean Theorem, JM=√252−152=20.
This means that the area of the triangle is 2×(20×15÷2)=300.
Now, recall the formula for inradius, which is Areasemiperimeter=30040=7.5
Now, recall the formula for circumradius, which is product of the side lengths4×Area=18,7501,200=15.625