Question

Find cos θ if sin θ = -5/13 and tan θ > 0.

a. -5/12
b. -13/5
c. -12/13
d. 12/5

Answer 1

c

Answer 2

soh cah toa
o = -5 h = 13
x^2 + (-5)^2 = 13^2 x^2 = 144 so x = a = 12
cos = -12/13

Answer 3

sin(x)^2 + cos(x)^2 =1
cos(x)^2 = 1- (-5/13)^2 = 144/169
cos(x)=+-12/13
because sin(x) is negative and tangent(x) is positive it must be in the third or forth quadrant. Therefore cos(x) must be negative

Answer 4

c