# Trig Ratios: Solve for x when x is between 0 and 360

• Nov 23rd 2010, 07:33 PM
tmas
Trig Ratios: Solve for x when x is between 0 and 360
Solve for x when x is between 0 and 360

tan2x+1=0
This is what i did:
tan2x+1=0
tan2x= -1

the places where tan = -1 between 0 and 360 are
135, 315, 495, and 675 (divided these by 2 to get the actual angles)

Actual angles are:
67.5,157.5,202.5,337.5

the answer in the back of the book is 0 degrees
I don't understand this??
What am i missing
• Nov 23rd 2010, 07:46 PM
skeeter
Quote:

Originally Posted by tmas
Solve for x when x is between 0 and 360

tan2x+1=0
This is what i did:
tan2x+1=0
tan2x= -1

the places where tan = -1 between 0 and 360 are
135, 315, 495, and 675 (divided these by 2 to get the actual angles)

Actual angles are:
67.5,157.5,202.5,337.5

the answer in the back of the book is 0 degrees
I don't understand this??
What am i missing

nothing, just a typo ...

0 degrees is not a correct solution ... tan(0) + 1 does not equal 0

0 < x < 360

0 < 2x < 720

tan(2x) = -1

2x = 135 , 315, 495, 675

x = 67.5, 157.5, 247.5, 337.5