Originally Posted by

**arccos** This is not always the case(as it seems so to me)

For example,

$\displaystyle 4cos\theta - 3sin\theta = Rsin(\theta - \alpha)$

....

Maximum value = 5 when, $\displaystyle sin(\theta - 53.1) = -1$

$\displaystyle \theta = 270(as \, sin-90 = sin(360-90)) + 53.1 = 323.1$(323.1 was the answer given in the textbook)

I know this may sound weird but the way I look at it is that if the brackets containing theta and alpha has a negative sign in it, i treat the sine graph as inverted(opens downwards before curving upwards),in this way, the minimum point coordinate on the x axis is smaller than the maximum point and hence I can deduce if my answer is correct or not. Seems to be the only pattern that I can find from the questions I have done involving Rsin.