Question

if sin a= 1/2 the find value of 3sin a -4 sina 3

Answer 1

sina=1/2
so
=3sina-4sina3
=3×1/2-4×1/2×3
=3/2-12/2
=3-12/2
=-9/2

Answer 2

Heya!

Since, sin a = 1/2

=) sin a = sin 30°

=) a = 30°

____________________

Then,

3 sin a - 4 sin a 3

= 3 sin 30° - 4 sin 30° 3

= 3 *1/2 - 4 * 1/2 * 3

= 3/2 - 6

= ( 3 - 12 )/2

= - 9 / 2

Hope it helps u.