Question and Answers Forum

All Questions      Topic List

Trigonometry Questions

Previous in All Question      Next in All Question      

Previous in Trigonometry      Next in Trigonometry      

Question Number 129234 by bemath last updated on 14/Jan/21

$$\cos {}^{2}47°+{\cos }^{2}73°+\cos 47°\cos 73°+\frac{1}{2}=?$$

Answered by liberty last updated on 14/Jan/21

$${(\cos 73°+\cos 47°)}^2-\cos 73°\cos 47°+\frac{1}{2}=$$$${\left(2\cos 60°\cos 13°\right)}^2-\frac{1}{2}(\cos 120°+\cos 26°)+\frac{1}{2}=$$$$\cos {}^{2}13°-\frac{1}{2}(-\frac{1}{2}+2\cos {}^{2}13°-1)+\frac{1}{2}=$$$$\cos {}^{2}13°+\frac{3}{4}-\cos {}^{2}13°+\frac{1}{2}=\frac{5}{4}$$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com