The Question is Incomplete The complete question with figure is below.
Answer:
Therefore the equation to solve for b is

Explanation:
Given:
In Right Angle Triangle ABC
∠C = 90°
BC = 5 cm
AB = 10 cm
∠A = 30°
To Find:
b = ?
Solution:
In Right Angle Triangle ABC Tangent identity we have

Substituting the values we get

Therefore the equation to solve for b is
