NCERT Class 7 Mathematics Solutions: Chapter 5 –Linear and Angles Exercise 5.1 Part 6

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Understanding of obtuse and acute angles

Understanding of Obtuse and Acute Angles

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1. 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, then the vertically opposite angles are always _______.

(vi) 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 _______.

Answer:

(i)

(ii)

(iii) Supplementary

(iv) Linear pair

(v) Equal

(vi) Obtuse angles

2. In the adjoining figure, name the following pairs of angles.

Given Figure in Adjoining Pair of Angle

(i) Obtuse vertically opposite angles

(ii) Adjacent complementary angles

(iii) Equal supplementary angles

(iv) Unequal supplementary angles

(v) Adjacent angles that do not form a linear pair

Answer:

(i) Obtuse vertically opposite angles means greater than and equal.

(ii) Adjacent complementary angles means angles have common vertex, common arm, non-common arms are on either side of common arm and sum of angles is .

(iii) Equal supplementary angles means sum of angles is and supplement angles are equal.

(iv) Unequal supplementary angles means sum of angles is and supplement angles are unequal.

(v) Adjacent angles that do not form a linear pair mean, angles have common ray but the angles in a linear pair are not supplementary.