CBSE NCERT Solutions for Class 7 Chapter 5

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CBSE NCERT Solutions for Class 7 Maths Chapter 5:

Question-1:

Identify which of the following pairs of angles are complementary and which are supplementary:
(i) 65º,115º
(ii) 63º,27º
(iii) 112º,68º
(iv) 130º,50º
(v) 45º,45º
(vi)80º,10º

Solution:

(i) 65º + 115º =180º.These are supplementary angles.
(ii) 63º + 27º =90º These are complementary angles.
(iii) 112º+ 68º =180º.These are supplementary angles
(iv) 130º+ 50º=180º.These are supplementary angles
(v) 45º+ 45º =90º These are complementary angles.
(vi)80º +10º =90º These are complementary angles.

Question-2:

An angle is greater than 45. Is this complementary angle greater than 45 or equal to 45 or less than 45?

Solution:

Let the complementary angles be x and y ,i.e , x+y=90
It is given that x>45
Adding y both sides, x+y>45+y
Thus, its complementary angle is less than 45.

Question-3:

Fill in the blanks:
(i) If two angles are complementary, then the sum of their measures is ______________
(ii) If two angles are supplementary, then the sum of their measures is _______________
(iii) Two angles forming a linear pair are _______________
(iv) If two adjacent angles are supplementary, they form a _______________
(v) If two lines intersect at a point and if one pair of vertically opposite angles are acute angles, then the other pair of vertically opposite angles are_______________

Solution:

(i) 90° (ii)1800 (iii)supplementary
(iv) Linear pair (v) equal (vi) obtuse angles

Question-4:

Find the angle which is equal to its complement:
Let one of the two equal complementary angles be x.

Solution:

∴x+x=90 => 2x =90 =>x=90/2 =45º
Thus 45º is equal to its complement.

Question-5:

Find the angle which is equal to its supplement.
Let one of the two equal supplementary angles be x.

Solution:

∴x+x=180 => 2x =190 =>x=180/2 =90º
Thus, 90 is equal to its supplement.