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Exercise #18 Double Angle Identities
2 2
sin 2 2sin cos
cos 2 cos sin
2
2
2cos 1
1 2sin
2
2 tantan 2
1 tan
Example Evaluate cos120 using the double angle formula. Example
If 4
sin5
and 3
cos5
, find tan 2 .
OR
OR
Example
Solve sin 2 sin over the interval 0,2 .
Example
Given that cos 0.9920
, evaluate cos
10
.
Try
Evaluate cos7
given that cos 0.9714
.
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