Pre Calculus
posted by Jessica Maths .
Use the sumtoproduct formulas to find the exact value of the given expression.
sin 150° + sin 30°

Sorry, I have figured out this one but cannot figure out this one
Use the sumtoproduct formulas to write the given expression as a product. sin 4θ − sin 2θ
Could you help me with this one instead please? 
sum of sines:
sinA + sinB = 2sin( (A+B)/2) cos( (AB)/2)
then:
sin 150° + sin 30° = 2sin 90° cos 60°
= 2(1)(1/2)
= 1
Difference of sines:
sinA  sinB = 2cos( (A+B)/2) sin( (AB)/2)
then:
sin 4θ − sin 2θ
= 2cos(3Ø)sin Ø
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