What's the value of x?

Question

What's the value of x if pi≤x≤3pi/2 and sin x=5 cos x?

Answer 1

 

Well, if sin x = 5cos x then we can say that tan x = 5 and x = arctan 5 = 78.60 degrees...you can convert that to radians, of course, by dividing by 180 and multiplying by pi, or by doing the arctan operation with your calculator in RADIAN mode.

 

THEN you have to add pi radians, to get into the third quadrant!