Given: cosθ= -4/5 , sin x = -12/13 , θ is in the third quadrant, and x is in the fourth quadrant; evaluate tan (θ +x) and sin (θ +x))

tan (θ+x)= -33/56

sin (θ+x)=33/65

Step-by-step explanation:

cosθ= -4/5 , sin x = -12/13

cosθ= -4/5; θ is in the third quadrant=> sinθ=-√(1-cos² θ)

sinθ=- √(1-16/25)=- √(9/25)=-3/5

sinx= -12/13; x is in the fourth quadrant=> cosx=+√(1-sin²x)

cosx=√(1-144/169)= √(25/169)=5/13

tgθ= sinθ/cosθ=(-3/5)/(-4/5)=3/4

tgx= sinx/cosx=(-12/13)/(5/13)= -12/5

tan (θ+x)=(tgθ+tgx)/(1-tgθ*tgx)

tan (θ+x)=(3/4-12/5)/(1+3/4*12/5)=(-33/20)/56/20)= -33/56

sin (θ+x)=sinθcosx+coxθsinx=-3/5 *5/13 +-4/5 * (-12/13)=-15/65+48/65=33/65

the answer is 99.