gurlsweetienawx

2023-02-22

How to find the value of $\mathrm{cos}(-90)$?

resymeguv48h

Beginner2023-02-23Added 7 answers

$\mathrm{cos}-\theta =\mathrm{cos}(360-\theta )=\mathrm{cos}\theta {\phantom{\rule{1ex}{0ex}}\text{since cos is +ve in IV Quadrant}}$

$\therefore \mathrm{cos}(-90)=\mathrm{cos}(360-90)=\mathrm{cos}90=0$

$\therefore \mathrm{cos}(-90)=\mathrm{cos}(360-90)=\mathrm{cos}90=0$