Question

sin(theta +alpha)sin(theta -alpha) =?

Answer 1

use the sine double angle formulas
it should be
(sin(theta)cos(alpha)+sin(alpha)cos(theta))*(sin(theta)cos(alpha)-sin(alpha)cos(theta))

Answer 2

oh i see thank you! can you help me with another question tan(45degrees +a) +tan(45degrees -a)

Answer 3

same deal, use the tan angle sum identity

[(tan(45 degrees)+tan(a))/(1-tan(45 degress)tan(a))]*[(tan(45 degrees)+tan(a))/(1-tan(45 degress)tan(a))]

then replace tan(45 degrees) with 1 since tan(45 degrees) =1