Can i get some help? :') I dont know what im doing

Use the given information to determine the exact trig value. cot theta = -square root of 5 / 2 , pi/2 < theta < pi, tan theta a.) - square root of 5 / 5 c.) - 2 square root of 5 / 5 b.) - square root of 5 / 2 d.) the answer isn't d, it was incorrect