Ask your own question, for FREE!
Mathematics 9 Online
OpenStudy (anonymous):

cos10 cos80 - sin10 sin80

OpenStudy (anonymous):

use "addition angle formula" in reverse \[\cos(a+b)=\cos(a)\cos(b)-\sin(a)\sin(b)\] with \(a=10,b=80\)

OpenStudy (anonymous):

\[\cos90 = 0\]

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Latest Questions
Arriyanalol: i need help
2 days ago 7 Replies 1 Medal
Arriyanalol: CONGRATS to me
2 days ago 8 Replies 2 Medals
Legomaster346: What colleges are good that are near Arab Alabama?
1 week ago 5 Replies 0 Medals
Arriyanalol: i need help
1 week ago 6 Replies 2 Medals
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!