Question

evaluate cosπ/8*cos2π/8*cos3π/8* cos4π/8
​

Answer 1

Step-by-step explanation:

The given expression is

=(1+cos8π)(1+cos83π)

=(1−cos83π)(1−cos8π)

=(1−cos28π)(1−cos283π)

=sin28πsin283π

=41{2sin83πsin8π}2

=41{cos4π−cos2π}2=81

Answer 2

Answer:

THE CORRECT ANSWER IS 0.

Step-by-step explanation:

$cos\frac{\pi }{8} * cos\frac{2\pi }{8} * cos\frac{3\pi }{8} * cos\frac{4\pi }{8} \\=cos\frac{\pi }{8} * cos\frac{2\pi }{8} * cos\frac{3\pi }{8} * cos\frac{\pi }{2} \\=cos\frac{\pi }{8} * cos\frac{2\pi }{8} * cos\frac{3\pi }{8} * 0 \\=0$