How to draw an angle of 120 ,105 and 150

1.

Firstly draw a line PQ as shown:

2. Now, place the compass at point P and adjust its opening more than half of PQ and draw an arc from P as shown below:

3. Let the point at which the drawn arc touches the line PQ is R.

4. Now, maintaining the same opening of compass, draw an arc from point R

Let us name the point as S.

5. From point S, again draw an arc.

Let us name the obtained point as T.

6. Join PT.

Hence, ∠TPQ = 120°

Kindly ask the remaining queries in different threads.

Regards