Sinasinb Formula Math
If we let a b in equations 2 and 3 we get the two identities sin2a 2sinacosa 12 cos2a cos2 a sin2 a.
Sinasinb formula math. 4 adding 1 and 2 then 3 and 4 and subtracting 3 from 4 we obtain sinacosb 1 2 sin a b sin a b cosacosb 1 2 cos a b cos a b sinasinb 1 2 cos a b cos a b. This video shows the formula for deriving the cosine of a sum of two angles. 2 cosacosb 2sin. Cos a b cosacosb sinasinb cos a b cosacosb sinasinb this gives cos a b cos a b 2sinasinb or in the form we prefer sinasinb 1 2 cos a b 1 2 cos a b.
These identities are useful in integration and computing laplace transforms. 11 5 double angle identities now a couple of easy ones.