Page 2 - ANS SUB

0
0
0
2x – 5 + x – 10 = 90
0
0
3x – 15 = 90
0
3x = 105
105 0
x =
3
0
x = 35
0
0
Therefore, the value of x for which the angles (2x – 5) and (x – 10) are the
0
complementary angles is 35 .
5. Find the angle whose complement is one third of its supplement.
0
Solution:Let the required angle as x
0
0
We know that the complement can be written as (90 – x) and the supplement
o
can be written as 180 – x

o
o
A/Q ,90 – x = (180 – x)

1
90 – x = 60 – x
3
1
x – x = 90- 60
3
2
x = 30
3
30×3
x =
2
0
x = 45
0
Therefore, the angle whose complement is one third of its supplement is 45 .
6 Define the following terms:
(i) Angle
(ii) Interior of an angle
(iii) Obtuse angle
(iv) Reflex angle
(v) Complementary angles
(vi) Supplementary angles
Solution:(i) Angle – When two rays originate from the same end point, then an
angle is formed.
(ii) Interior of an angle – The interior of ∠BAC is the set of all points in its plane
which lie on the same side of AB as C and also on the same side of AC as B.
o
0
(iii) Obtuse angle – An angle whose measure is more than 90 but less than 180
is called an obtuse angle.
(iv) Reflex angle – An angle whose measure is more than 180o but less than
360o is called a reflex angle.
(v) Complementary angles – Two angles are said to be complementary, if the
0
sum of their measure is 90 .
(vi) Supplementary angles – Two angles are said to be supplementary if the sum

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