RS Aggarwal Class 9 Solutions Angles, Lines and Triangles

RS Aggarwal Class 9 Solutions Angles, Lines and Triangles

Exercise 4A

Question 1:

(i) Angle: Two rays having a common end point form an angle.

(ii) Interior of an angle: The interior of ∠AOB is the set of all points in its plane, which lie on the same side of OA as B and also on same side of OB as A.

(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 180° but less than 360° is called a reflex angle.

(v) Complementary angles: Two angles are said to be complementary, if the sum of their measures is 90o.

(vi) Supplementary angles: Two angles are said to be supplementary, if the sum of their measures is 180°.

Question 2:

∠A = 36° 27' 46" and ∠B = 28° 43' 39"

∴ Their sum = (36° 27' 46") + (28° 43' 39")

Therefore, the sum ∠A + ∠B = 65° 11' 25"

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