In △ ABC, a is an obtuse angle, Sina = 3 / 5, C = 5, B = 4

In △ ABC, a is an obtuse angle, Sina = 3 / 5, C = 5, B = 4

There is a formula a = 1 / 2cbsin a = 1 / 2 * 5 * 4 * 3 / 5 = 6
I hope you can adopt it