Mathematics - Quadratic Equation Question with Solution | TestHub

$(\cos p-1)x^2+(\cos p)x+\sin p=0$ Discriminant of (1) is given by $D={\cos }^{2}p-4(\cos p-1)\sin p$ $={\cos }^{2}p+4(1-\cos p)\sin p$ Note that ${\cos }^{2}p\ge 0,1-\cos p\ge 0$. Thus, $D\ge 0$ if $\sin p\ge 0$ i.e. if $p\in (0,\pi )$.