Determine them. 0 =90 -a 0 = b d Continuing to apply the sine and cosine functions to right triangles, label the remaining sides in terms of a and B : h d= factd = C Now, by comparing e and f , derive the angle addition formula B for sine: sin(a + () =9. Let a be in quadrant III with sin(@) = -= , and let / be in quadrant II with cos(B) = -- 13 . What is sin(a + B) ? What is cos(a + B) ? . What quadrant is a + / in