Evaluate cos 48^(@) cos 42^(@) - sin48^(...

Evaluate `cos 48^(@) cos 42^(@) - sin48^(@) sin 42^(@)`

Text Solution

Verified by Experts

`= Cos48^(@)cos42^(@)- Sin 48^(@)Sin 42^(@)`
`= Sin (90^(@)- 48^(@)) sin (90^(@)- 42^(@)) - Sin48^(@) Sin 42^(@)`
`= Sin 42^(@) Sin 48^(@)- Sin 48^(@) Sin 42^(@) =0`

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none

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`-1`

`-1//2`

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sin 6^(@) sin 42^(@) sin66^(@) sin 78^(@) =

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`1//8`

`1//16`

`1//64`