cos 4x = sin x
2cos^2 2x - 1 = sin x
2(1 - 2sin^2 x)^2 - 1 = sin x
Now you have to solve a quartic in sin x.
You know from the very 1st equation that
pi/2 is a solution.
The others are not so simple.
Visit wolframalpha.com and enter
solve cos 4x = sin x
to see the graphs and the solutions.
Find one solution for each equation.
1. cos 4theta = sin theta
2. tan 4theta = cot (20^0 + 20)
Write the function sin (B + 35^0) in terms of its cofunction.
1 answer
1 answer