I have been trying to solve this question but have so far been unable to do so as the question does not seem to be "cohesive throughout". Here is my reasoning:
The question is: given that $\cos A=−3/5$, $\sin B=−5/13$, and both $A$ and $B$ are in the 3rd quadrant, find $\cos^2(A)+\sin^2(A)$.
I know of the trigonometric identity $\cos^2(\theta)+\sin^2(\theta)=1$. In this identity however, $\theta$ is in place of $A$. cos $A$ is a fraction in the case of the question, however I often see $\theta$ as in the radian or degree form. Does this mean that the trigonometric identity does not apply to the question or is my assumption based on familiarity incorrect?
Also, if the identity were to apply to the question, does the question have an answer or not? When I attempted to solve this question, I did not get $1$ as the answer.