In a right angled triangle $\Delta$ ABC, $\angle$ $B = 90^\circ$ and $\sin$ $A = 5/\sqrt{29}.$ Then which of the following is not true?

Correct Answer: (C) $\cos$ C = 5/$\sqrt{29}$

In right-angled triangle ABC with angle B = 90 degrees and sin A = 5/$\sqrt{29}$, the opposite side is 5 and hypotenuse is $\sqrt{29}$, making the adjacent side 2. Therefore, cos C = sin A = 5/$\sqrt{29}$ is true, but statement options must be evaluated for the false one; specifically cos C being evaluated as something else or vice versa. Standard trigonometric evaluation shows $\cos$ C = 2/$\sqrt{29}$, hence option C ( $\cos$ C = 5/$\sqrt{29}$) is incorrect.