If theta is on angle in Quadrant represent sin theta in term

If theta is on angle in Quadrant represent sin theta in terms of cos theta. Use the parent function to sketch: a) y = -1/2 cos(2x + pi/2) b) y = -2 sin (1/2x + pi) c) y = 1/2 tan(x/z)

Solution

9) sinA = -4/5 , A is in QIII , cosB = 3/17   , B is in QI ( this is what i can see )

cosA = -3/5 ; sinB = sqrt(280)/17

sin(A -B) = sinAcosB - sinBcosA

= (-4/5)(3/17) - (sqrt(280)/17)*(-3/5)

= ( -12 - sqrt280)/85

cos(A -B) = cosAcosB +sinAsinB

= (-3/5)(3/17) +(-4/5)(sqrt(280)/17)

= ( -9 -4sqrt280)/85

tan(A - B) = sin(A - B)/cos(A - B)

= (12 +sqrt280)/(9 +4sqrt280)