- #1
Cod
- 325
- 4
For some reason, I cannot comprehend the concepts behind this. I read the example problems over and over; however, I still cannot understand the process when I go to study or do work on it.
Just to refresh your minds, the double-angle formulas:
sin2x = 2(sinx)(cosx)
cos2x = cos^2x - sin^2x = 1 - 2sin^2x = 2cos^2x-1
tan2x = 2tanx/1-tan^2x
The book example:
If cosx = -2/3 and x is in quadrant II; find sin2x and cos2x.
If someone could explain the processes when using these formulas to solve problems, I'd greatly appreciate it. The book just isn't helping me any.
Just to refresh your minds, the double-angle formulas:
sin2x = 2(sinx)(cosx)
cos2x = cos^2x - sin^2x = 1 - 2sin^2x = 2cos^2x-1
tan2x = 2tanx/1-tan^2x
The book example:
If cosx = -2/3 and x is in quadrant II; find sin2x and cos2x.
If someone could explain the processes when using these formulas to solve problems, I'd greatly appreciate it. The book just isn't helping me any.