2cos2θ−cosθ−1=0 for −180°≤θ≤180°
i don't get how it is solved

Is the product of seventeen negative numbers, positive or negative ?

If an athlete can bike 6 miles in 25 minutes, how many miles will he bike in an hour and half if he continues to bike at the same rate?

An assembly consists of two mechanical components. suppose that the probabilities that the first and second components meet specifications are 0.87 and 0.84. assume that the components are independent. determine the probability mass function of the number of components in the assembly that meet specifications. x