Use the given information to find a sin st b tanst and c the

Use the given information to find (a) sin (s+t), (b) tan(s+t), and (c) the quadrant of s+t. cos s=4/5 and cos t=15/17, s and t in quadrant III.

cos s=-4/5 here adjacent = 4 and hupotenuse=-5

therefore opposite=-3

hence sin s=-3/5

similarly sin t= -8/ 17

sin(s+t)= sin s cos t + cos s sin t

= -3/5 * -15/17 + -4/5 * -8/17= 45/ 85 + 32/85 =77/85

Cos(s+t)=cos cost - sins sint

= -4/5 * -15/17 - -3/5 * -8/17= 60/85 - 24/85= 36/85

tan (s+t)= sin(s+t)/cos(s+t)= -77/24