Thread: Solving Trigonometric Equations

Solve the following equation algebraically. Give a general solution.

3cos²x+cosx=2

Originally Posted by vanessa81929

Solve the following equation algebraically. Give a general solution.
3cos²x+cosx=2

Can you solve

Originally Posted by vanessa81929

Solve the following equation algebraically. Give a general solution.

3cos²x+cosx=2

can you finish?

cosx= 2/3 cosx= -1

what do you do next?

Originally Posted by vanessa81929

cosx= -2/3 cosx= -1

what do you do next?

in the interval ...

... and

... you tell me what x value on the unit circle has a cosine of -1


if you want all solutions, add integer multiples of to all three solutions.

For the first one, x= 0.841+2npi

And for the second one, x=pi+2npi

Where are you getting a third solution from?

has two solutions, one in quad I and one in quad IV


for , the general solution should be written ...



... and put away the calculator.