Mark the Correct alternative in the following:

The value of sin 50^o – sin 70^o + sin 10^o is equal to

Mark the Correct alternative in the following:

If sin α + sin β = a and cos α – cos β = b, then

Mark the Correct alternative in the following:

cos 35^o + cos 85^o + cos 155^o =

Mark the Correct alternative in the following:

sin 47^o + sin 61^o – sin 11^o – sin 25^o is equal to

Mark the Correct alternative in the following:

If cos A = m cos B, then =