Which choice is an irrational number?

Which expression converts 45 degree to radians

Which of the following is the explicit rule for a geometric sequence defined a recursive formula of a -5a for which the first term is 23?

If the altitude is drawn to the hypotenuse of a right triangle, then the two triangles formed are similar to the original triangle and to each other. which set of triangles shows the similar triangles created by the altitude in the diagram?