By the law of Sines we got the equation
15
30
= 𝑠𝑖𝑛𝐶° So we got angle C is 43.16°
𝑠𝑖𝑛20°
and angle A is 180°-20°-43.16° = 116.84° By the law of Sines again we got
α
𝑠𝑖𝑛43.16°
Solving the equation we got the value of α is 29.99
By the law of Cosines we got the equation
𝑎
𝑠𝑖𝑛20°
30
= 𝑠𝑖𝑛𝐶°
15
𝑠𝑖𝑛20°
=