 How do i solve cos (-60(degrees)) to exact values? Cynthia Bell 2021-12-26 Answered
How do i solve cos (-60(degrees)) to exact values?

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Explanation:
$$\displaystyle{\cos{{\left(-{60}^{\circ}\right)}}}$$
first convert $$\displaystyle{60}^{\circ}$$ in radians just for the sake of convenience of problem solving in trigonometry. since $$\displaystyle\pi\ \text{ radian }\ ={180}^{\circ}\Rightarrow{60}^{\circ}={\left({\frac{{\pi}}{{{3}}}}\right)}\ \text{ radians}$$
now, since $$\displaystyle{\cos{{\left(-\theta\right)}}}={\cos{\theta}}.$$
so, $$\displaystyle{\cos{{\left(-{\frac{{\pi}}{{{3}}}}\right)}}}={\cos{{\left({\frac{{\pi}}{{{3}}}}\right)}}}={\frac{{{1}}}{{{2}}}}$$ (a standard value and should be memorised)
Not exactly what you’re looking for? jgardner33v4
$$\displaystyle{\cos{{\left(-{x}\right)}}}={\cos{{\left({x}\right)}}}$$
$$\displaystyle{\cos{{\left(-{60}\right)}}}={\cos{{\left({60}\right)}}}$$
$$\displaystyle={\frac{{{1}}}{{{2}}}}={0.5}$$ Vasquez
Thank you, it was very helpful