This circle has the centre at the origin and a radius of 1 unit. The point P can move around the circumference of the circle. At point P the \(x\)-coordinate is \(\cos{\theta}\) and the \(y ...

At point P the \(x\)-coordinate is \(\cos ... sin{x}\) four times in the interval \(-360^\circ \leq \theta \leq 360^\circ\) so there are four solutions. There is a line of symmetry at \(x = 90 ...