You probably jsut need to use law of cosines in order to solve for angle A

or
The answer to the mathematics question presented above is 'True'. It is correct to say that in (r theta), the value of r can be negative. A negative radius can be used when it comes to graphing a "polar'' function. Thus, the answer to the question is 'true'.
Answer:
19872 is your answer
Step-by-step explanation:
8. Now I deserve brainliest:)