Question:
Construct a ΔABC in which BC = 4.8 cm, ∠B = 45° and ∠C = 75°. Measure ∠A.
Solution:
Steps of construction:
1. Draw a line segment BC = 4.8 cm.
2. Construct $\angle C B X=45^{\circ}$.
3. Construct $\angle B C Y=75^{\circ}$.
4. The ray $B X$ and $C Y$ intersect at $A$.
Thus, $\triangle A B C$ is the required triangle.
When we measure $\angle A$, we get $\angle A=60^{\circ}$.