Selina Concise Class 6 Math Chapter 22 Angles (with Their Types And Properties) Exercise 22B Solution
EXERCISE 22B
(1) Write the complement angle of:
(i) 90o – 45o = 45o
(ii) (90o – xo)
(iii) 90o – (x – 10)o
= 90o – xo + 10o
= 100o – xo
(iv) 90o – (20o + yo)
= 90o – 20o – yo
= 70o – yo
(2) Write the supplement angle of:
(i) 180o – 49o = 131o
(ii) 180o – 111o = 69o
(iii) 180o – (x – 30)o
= 180o – x + 30o
= 210o – xo
(iv) 180o – (20o + yo)
= 180o – 20o – yo
= 160o – yo
(3) Find the complement angle of:
(4) Find the supplement angle of:
(5) Find the angle:
(i) 45o
(ii) 90o
(6) Let the angles be 7x and 8x.
∴ 7x + 8x = 90
⇒ 15x = 90
⇒ x = 6
Therefore, the angles are (7 × 6) = 42o and (8 × 6) = 48o
(7) Let the angles be 7x and 11x.
∴ 7x + 11x = 180
⇒ 18x = 180
⇒ x = 10
Therefore, the angles are (7 × 10) = 70o and (8 × 10) = 80o.
(8) (2x – 7) + (x + 4) = 90
⇒ 2x – 7 + x + 4 = 90
⇒ 3x – 3 = 90
⇒ 3x = 90 + 3
⇒ 3x = 93
⇒ x = 31
(9) (3x + 15) + (2x + 5) = 180
⇒ 3x + 15 + 2x + 5 = 180
⇒ 5x + 20 = 180
⇒ 5x = 180 – 20
⇒ 5x = 160
⇒ x = 32
(10) For an angle xo, find:
(i) (90o – xo)
(ii) (180o – xo)
(iii) (180 – x)o = 3(90 – x)o
⇒ 180 – x = 270 – 3x
⇒ -x + 3x = 270 – 180
⇒ 2x = 90
⇒ x = 45