Question Number 26135 by JI Siam last updated on 21/Dec/17
$$\mathrm{Prove}\:\mathrm{that}\:\mathrm{b}=\mathrm{2asin}^{\mathrm{2}} \theta\:; \\ $$$$\mathrm{when}\:\mathrm{acos}\theta−\mathrm{bsin}\theta=\mathrm{c}\:\mathrm{and}\:\theta=\mathrm{45}° \\ $$
Commented by mrW1 last updated on 21/Dec/17
$${It}\:{is}\:{not}\:{true}\:{that}\:{b}=\mathrm{2}{a}\:\mathrm{sin}^{\mathrm{2}} \:\theta\:{if}\:{c}\neq\mathrm{0}. \\ $$
Answered by ajfour last updated on 21/Dec/17
$${b}={a}\:\:{then}\:\:{c}=\mathrm{0}\:. \\ $$