Question

求值（1）sinπ/64cosπ/64cosπ/32cosπ/16cosπ/8 （2）sin10°sin30°sin50°sin70°速度！！！

Answer 1

（1）sinπ/64cosπ/64cosπ/32cosπ/16cosπ/8
=1/2sinπ/32cosπ/32cosπ/16cosπ/8
=1/4 sinπ/16cosπ/16cosπ/8
=1/8sinπ/8cosπ/8
=1/16 sinπ/4=√2/32
(2)
sin10°sin30°sin50°sin70°
=1/2cos20ºcos40ºcos80º
= 2sin20ºcos20ºcos40ºcos80º/(4sin20º)
=2sin40ºcos40ºcos80º/(8sin20º)
=2sin80ºcos80º/(16sin20º)
=sin160º/(16sin20º)
=sin20º/(16sin20º)
=1/16