Question 383003
Evaluate the expression using trig identities. State the identity that you use. 

sin(pi/12)sin(5pi/12) ]

= sin(15 degrees)(sin(75 degrees)
= sin(45-30)*sin(45+30)
----
= [sin45cos30+cos45*sin30]*[sin45cos30-cos45sin30]
----
= [sin45cos30]^2 - [cos45sin30]^2
=  [(sqrt(2)/2)(sqrt(3)/2)]^2 - [(sqrt(2)/2)(1/2)]^2
= [(sqrt(6)/4]^2 - [(sqrt(2)/4]^2
= 6/16 - 2/16
= 1/4
=====
Cheers,
Stan H.