Which statement about these triangles are true

Solve the system of equations. y= 2x y= x^2 - 15

Find the domain of the following expression: 1/(√x)-2

Asquare has a side that measures 11 units. what is the area of a circle with a circumference that equals the perimeter of the square? use 3.14 for π, and round your answer to the nearest hundredth. 1519.76 units2 379.94 units2 616.56 units2 154.14 units2