Given the equation cos2x +7cosx-3 = 0 find the tan value of x
I've tried using 2cos^2x-1 +7cosx-3=0 but I don't know what to do next??
and one more: sin 105° - sin 15° = ???
Please help. Thanks
Hello, SodaCup!
We have: .Given the equation: . , find
I've tried using: .
but I don't know what to do next.
How about combining the -1 and -3?
Factor: .
And we have two equations to solve:
. .
. .
Therefore: .
We can use two identities: .Evaluate: .
So that: .
Then: .
Note that: .