for x ≠ kπ, k∈Z show that: sin8x / 8sinx = cosx.cos2x.cos4x deduce the value of E = cosπ / 7.cos2π / 7.cos4π / 7 ?
for #x ≠ kπ, k∈Z# show that:
#(sin8x) / (8sinx) = cosx xxcos2x xxcos4x#
deduce the value of #E = cosπ / 7xx(cos2π) / 7xx(cos4π) / 7#
for
deduce the value of
1 Answer
Jan 27, 2018
The product should have been written as
Explanation:
Following Eshan S's answer we provevthe general trigonometric identity with the double angle formula for sines:
Then putting
But also