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 90596 by I want to learn more last updated on 24/Apr/20

$$\mathrm{If}\sin \left(28\right)=\mathrm{a}\mathrm{and}\cos \left(32\right)=\mathrm{b}$$$$\mathrm{Find}\left(\mathrm{i}\right)\cos \left(28\right)$$$$\left(\mathrm{ii}\right)\cos \left(64\right)$$$$\left(\mathrm{iii}\right)\sin \left(4\right)$$

Answered by mahdi last updated on 25/Apr/20

$$\mathrm{i})\cos 28=\sqrt{1-{\sin }^{2}28}=\sqrt{1-{\mathrm{a}}^2}$$$$\mathrm{ii})\cos 64=\cos (32+32)={2\cos }^{2}32-1={2\mathrm{b}}^2-1$$$$\mathrm{iii})\sin 4=\sin (32-28)=\sin 32.\cos 28-\sin 28.\cos 32$$$$=\mathrm{a}\sqrt{1-{\mathrm{b}}^2}-\mathrm{b}\sqrt{1-{\mathrm{b}}^2}$$

Commented by I want to learn more last updated on 25/Apr/20

$$\mathrm{Thanks}\mathrm{sir}$$

Commented by $@ty@m123 last updated on 25/Apr/20

$$Ithinkweshouldavoidanswering$$$$suchtypesofquestion,whichhelps$$$$studentstodotheirhomework.$$$$Itismisuseofthisforum.$$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com