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# Q.1 Find the value of the unknown x in the following diagrams:

(i) we know that sum of all angle of a triangle = 180
$$\angle$$ x + 50° + 60° = 180°
Or, $$\angle$$ x + 110° = 180°
$$\therefore$$ $$\angle$$x = 180° – 110° = 70°

(ii) we know that sum of all angle of a triangle = 180
$$\angle$$x + 90° + 30 = 180° [$$\triangle$$ is right angled triangle]
Or, $$\angle$$x + 120° = 180°
Or, $$\angle$$x – 180° – 120° = 60°
(iii) we know that sum of all angle of a triangle = 180
$$\angle$$x + 30° + 110° =180°
Or, $$\angle$$x + 140° = 180°
$$\therefore$$ $$\angle$$x = 180° – 140° = 40°

(iv ) we know that sum of all angle of a triangle = 180
$$\angle$$x + $$\angle$$x + 50° = 180°
Or, 2x + 50° = 180°
Or, 2x = 180° – 50°
Or, 2x = 130°
$$\therefore$$ x=130/2=65°

(v) we know that sum of all angle of a triangle = 180
$$\angle$$x + $$\angle$$x +$$\angle$$x =180°
Or, 3 $$\angle$$x = 180°
$$\therefore$$ $$\angle$$x=180°/3=60°

(vi) we know that sum of all angle of a triangle = 180
x + 2 x + 90° = 180° ($$\triangle$$ is right angled triangle)
Or, 3x + 90° = 180°
Or, 3x = 180° – 90°
Or, 3x = 90°
$$\therefore$$ x=90/3=30°