In ▵ABC, b=10, B=40 degree, and A=30 degree. Calculate a to the nearest tenth

Answer 1

Since this isn't a right triangle, you can't use your basic trig functions. However, you can use the law of sines, which states:

b/sinB = a/sinA = c/sinC

Since I know B, A and b, I'm going to solve for a first:

10/sin40 = a/sin30

Cross multiply:

asin40=10sin30

Get a by itself:

a = 10sin30/sin40

a = 7.8

Can you use the same method to find c? Hint, you can find C by remembering all angles in a triangle add up to 180 degrees.