The two shorter sides of a triangle are 9 and 12. what is a possible length to make length of the third side to make the triangle obtuse with obtuse

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Abird on top of a 200 ft bridge tower sees a man standing on the lower part of the bridge (which is 50 ft above the ground). the angle of depression from the bird is 26 ̊. how far is the man from the base of the bridge tower? with explanation and pictures .

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.