Data: Constructing an angle of 90° at the initial point of a given ray.
Steps of Construction:
1. Draw AB straight line.
2. Taking A as centre and any radius draw an arc and intersect AB at C.
3. Taking C as centre with same radius draw an arc which intersect at D.
4. With same radius taking D as centre, it intersects at E.
5. With centres E and D with same radius draw two arcs which meet both at F.
6. If AF is joined, AB straight line is the line in the point A with 90°,
i.e., AF.
In the above construction ∠DAB = 60° and ∠DAE = 60°.
Angular bisector of ∠DAE is AF.
∴ ∠DAF = ∠EAF = 30°
∴∠BAF = ∠DAB + ∠DAE = 60°+ 30°
∴∠BAF = 90°.
