Question

sin10 *sin30* sin50* sin70=1/14

Answer 1

write correctly
1/14 not
1/16

sin10.1/2.sin50.sin70 =1/16
1/2sin10.1/2[2sin50sin70]
1/4.sin10.[cos(-20)-cos120]
1/4sin10[cos20-(-1/2)]
1/8sin10.[2cos20+1]
1/8.2sin10cos20+sin10
1/8.sin30-sin10+sin10
1/8sin30
1/8.1/2
1/16.........................Proved