trig
posted by Kenneth on .
how do you work find sin (aB)beta sign. sin a = 12/13,a lies in quadrant II,and cos B = 15/17, B lies in quadrant I.

Can't quite figure out some of the verbage, but
if A is in QII and sinA = 12/13, the cosA = 5/13
if B is in QI and cosB = 15/17, then sinB = 8/17
So,
sin(AB) = sinAcosB  cosAsinB
= (12/13)(15/17)  (5/13)(8/17)
= 180/221 + 40/221 = 220/221