Simple..A cyrcle first of all is a 360 degree angle...as a result
X=360-115-105-60
X=80 degrees
They got it wrong it is actually k=8
The pythagorean theorem says that a² + b² = c²
You're given the b and the c so substitute the values in: a² + 12² = 15²
a² + 144 = 225; subtract 144 from both sides
a² = 81; square root each side
a = 9, or choice C
3(4)+6
12+6
The answer is 18
