Question
use an appropriate half-angle formula to find the exact value ofthe expression.
tan22.5
write the product as a sum
sinxsin5x
write the sum as a product
sin2x-sin7x
tan22.5
write the product as a sum
sinxsin5x
write the sum as a product
sin2x-sin7x
Answers
JQuiroz
sinxsin5x
sinucosv= 1/2[cos(u-v)-cos(u+v)]
= 1/2[cos(x-5x)-cos(x+5x)]
= 1/2[cos(-4x)-cos(6x)]
= 1/2cos4x-1/2cos6x
sinucosv= 1/2[cos(u-v)-cos(u+v)]
= 1/2[cos(x-5x)-cos(x+5x)]
= 1/2[cos(-4x)-cos(6x)]
= 1/2cos4x-1/2cos6x