Question Number 174853 by Mastermind last updated on 12/Aug/22
$$\mathrm{By}\:\mathrm{first}\:\mathrm{principle},\:\mathrm{solve}\:\mathrm{cos}^{\mathrm{2}} \mathrm{x}\:+\:\mathrm{sin}^{\mathrm{2}} \mathrm{x}=\mathrm{1} \\ $$
Commented by daus last updated on 13/Aug/22
$${what}\:{do}\:{you}\:{means}\:{by}\:{first}\:{principle}? \\ $$
Commented by Mastermind last updated on 13/Aug/22
$$\mathrm{Differentiate}\:\mathrm{by}\:\mathrm{first}\:\mathrm{principle} \\ $$