Question
Given $\sin (a)=\frac{2}{3}$ and $\cos (b)=-\frac{1}{4},$ with $a$ and $b$ both in the interval $\left[\frac{\pi}{2}, \pi\right):$a. Find $\sin (a+b)$b. Find $\cos (a-b)$
Step 1
$ This means that both $a$ and $b$ are in the second quadrant, where sine is positive and cosine is negative. Show more…
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