Question

cos π/15 * cos 2π/15 * cos4π/15 * cos8π/15

Answer 1

=[1/(sin π/15)]*sinπ/15 *cos π/15 * cos 2π/15 * cos4π/15 * cos8π/15

=[1/(sin π/15)]*(1/2)*sin2π/15 * cos 2π/15 * cos4π/15 * cos8π/15

=[1/(sin π/15)]*(1/4)*sin4π/15 * cos4π/15 * cos8π/15

=[1/(sin π/15)]*(1/8)*sin8π/15 * cos8π/15

=[1/(sin π/15)]*(1/16)*sin16π/15

=[1/(sin π/15)]*(1/16)*sin(π+π/15 )

=[1/(sin π/15)]*(1/16)*sinπ/15

=1/16