(i) 45°
Construction:
1. Drawn the base ray PQ.
2. Placed the centre of the protractor at the vertex P. Lined up the ray PQ with the 0° line. Then drawn and labelled a pointed (R) at the 45° mark on the inner scale (a) anticlockwise and (b) outer scale (clockwise)
3. Removed the protractor and drawn at PR to complete the angle
Now ∠P = ∠QPR – ∠RPQ = 45°.
(ii) 120°
Construction:
1. Placed the centre of the protractor at the vertex X. Lined up the ray XY with the 0° Line. Then draw and label a point Z at 120° mark on the (a) inner scale (anti-clockwise) and (b) outer scale (clockwise).
2. Removed the protractor and draw XZ to complete the angle.
Now, ∠X = ∠ZXY = ∠YXZ = 120°.
(iii) 65°
Construction:
1. Placed the centre of the protractor at the vertex A. Line up the ray AB with the 0° line. Then draw and label a point C at the 65° mark on the (a) inner scale (anti-clockwise) (b) outer scale (clockwise).
2. Removed the protractor and draw AB to complete the angle.
Now ∠A = ∠BAC = ∠CAB = 65°.
(iv) 135°
Construction:
1. Placed the centre of the protractor at the Vertex A. Lined up the ray EG with the 0° line. Then draw and label a point F at the 135° mark on the (a) inner scale (anti-clockwise) and (b) outer scale (clockwise)
2. Removed the protractor and draw EF to complete the angle.
Now ∠E = ∠FEG = ∠GEF = 135°.
(v) 0°
Construction:
1. Placed the centre of the protractor at the vertex G. Lined up the ray GH with the 0° line. Then draw and label a point I at the 0° mark on the
(a) inner scale (anti-clockwise)
(b) outer scale (clockwise)
2. Removed the protractor and seen GI lies exactly on GH
Now ∠G = ∠HGI = ∠IGH = 0°, which is a zero angle.
(vi) 180°
Construction:
1. Placed the centre of the protractor at the vertex I. Lined up the ray IJ with the 0° line. Then draw and labelled a point K at the 180° mark on the (a) inner scale (anticlockwise) (b) outer scale (clockwise)
2. Removed the protractor and draw IK to complete the angle.
Now ∠I = ∠JHK = ∠KIJ = 180°, which is a straight Angle.
(vii) 38°
Construction:
1. Placed the centre of the protractor at the vertex L. Lined up the ray LM with the 0° line. Then draw and label a point N at 38° mark on the (a) inner scale (anticlockwise) and (b)*huter scale (clockwise).
2. Removed the protractor and draw LN to complete the angle.
Now ∠L = ∠MLN = ∠NLM = 38°.
(viii) 90°
Construction:
1. Placed the centre of the protractor at the vertex ‘O’. Lined up the ray OP with the 0° line. Then draw and label a point Q at 90° mark on the (a) inner scale (anticlockwise) and (b) outer scale (clockwise)
2. Removed the protractor and draw OQ to complete the angle.
Now ∠O = ∠POQ = ∠QOP = 90°.
