Question 1: Find the complement of each of the following angles:
Answer: (i) 70°, (ii) 27°, (iii) 33°
Question 2: Find the supplement of each of the following angles:
Answer: (i) 75°, (ii) 93°, (iii) 26°
Question 3: Identify which of the following pairs of angles are complementary and which are supplementary.
Answer: (i) Supplementary, (ii) Complementary, (iii) Supplementary, (iv) Supplementary, (v) Complementary, (vi) Complementary
Question 4: Find the angle which is equal to its complement.
Answer: 45° (As is clear from option (v) of previous question)
Question 5: Find the angle which is equal to its supplement.
Question 6: In the given figure, ∠1 and ∠2 are supplementary angles. If ∠1 is decreased, what changes should take place in ∠2 so that both the angles still remain supplementary?
Answer: ∠2 should increase
Question 7: Can two angles be supplementary if both of them are:
Answer: (i) No, (ii) No, (iii) Yes
Question 8: An angle is greater than 45°. Is its complementary angle greater than 45° or equal to 45° or less than 45°?
Answer: Less than 45°
Question 9: In the adjoining figure:
Answer: (i) Yes, (ii) No, (iii) Yes, (iv) Yes, (v) Yes, (vi) Sum of °3 and °3
Question 10: Indicate which pairs of angles are:
Answer: (i) ∠1 and ∠4 (ii) ∠5 and ∠1 & ∠5 and ∠4
Question 11: In the following figure, is °1 adjacent to °2? Give reasons.
Answer: They do not have common vertex. So, they are not adjacent angles.
Question 12: Find the values of angles x, y and z in each of the following:
Answer: (i) `∠x-55°` (Vertically opposite angles)
`∠x+∠y=180°` (Linear pair of angles)
Now, `∠z=∠y` (Vertically opposite angles)
Thus, `x=55°`, `y=125°` and `z=125°`
Answer: (ii) `∠z=40°` (Vertically opposite angles)
`∠40°+x+25°=180°` (Angles on same side of a line)
Now, `∠y=∠x=115°` (Vertically opposite angles)
Thus, `x=115°`, `y=115°` and `z=40°`
Question 13: Fill in the blanks:
Answer: (a) 90°, (b) 180°,(c) Supplementary, (d) Linear pair, (e) equal, (f) Obtuse angles
Question 14: In the adjoining figure, name the following pairs of angles.
Answer: (a) ∠AOD and ∠BOC, (b) ∠AOB and ∠AOE, (c) ∠BOE and ∠EOD, (d) ∠AOE and ∠EOC, (e) ∠EOD and ∠DOC
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