How do you find the solution to $25 {cos}^{2} θ - 4 = 0$ $25cos^2theta-4=0$ if $0 \leq θ < 360$ $0<=theta<360$ ?

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Answer 1 · 2016-12-02T18:01:34

The value of the angle $θ$ $theta$ is ${cos}^{- 1} (\pm \frac{2}{5})$ $cos^(-1)(+-2/5)$ .

The givenequation is $25 {cos}^{2} θ - 4 = 0$ $25cos^2theta-4=0$ .
$:.25cos^2theta=4$ .

$:.cos^2theta=4/25$ .

$:.cos theta=+-2/5$ .

Now, the range of cosine of a certain angle is:
$-1<=costheta<=+1$ .

So, the above value of cosine of the angle, $theta$ is true for certain values of $theta$ .

$:.theta=cos^(-1)(+-2/5)$ . (Answer).

How do you find the solution to 25cos^2theta-4=025cos2θ−4=025cos^2theta-4=0 if 0<=theta<3600≤θ<3600<=theta<360?