Question

8sin10°×sin50°×sin70°

Answer 1

8cos10sin10*sin50*sin70 =4sin
cos10

4sin20*cos20*sin70 =2sin40
cos10 cos (90

sin80=1
sin80

Answer 2

Answer:

8 sin 10 sin 50 sin 70

= 4 sin 10 [2 sin 50 sin 70]

= 4 sin 10 [cos (50 -- 70) -- cos (50 + 70)]

= 4 sin 10 [cos 20 -- cos 120]

= 2 [2 sin 10 cos 20] -- 2 [2sin 10 cos 120]

= 2 [sin 30 -- sin 10] + 2 sin 10

= 2 (1/2) -- 2 sin 10 + 2 sin 10

= 1