Practice Set 17.2 8th Std Maths Answers Chapter 17 Circle: Chord and Arc
Solution & Step-by-Step Answer:
diameter PQ ⊥ diameter RS … [Given] ∴ m∠PCS = m∠SCQ = m∠PCR = m∠RCQ = 90° The measure of the angle subtended at the centre by an arc is the measure of the arc. ∴ m(arc PS) = m∠PCS = 90° …(i) m (arc SQ) = m∠SCQ = 90° …(ii) ∴ m(arc PS) = m(arc SQ) … [From (i) and (ii)] ∴ arc PS ≅ arc SQ … [If the measures of two arcs of a circle are same, then the two arcs are congruent] m(arc PR) = m∠PCR = 90°...(iii) m (arc RQ) = m∠RCQ = 90° … (iv) ∴ m(arc PS) = m(arc PR) = m(arc RQ) … [From (i), (iii) and (iv)] ∴ arc PS ≅ arc PR ≅ arc RQ … [If the measures of two arcs of a circle are same, then the two arcs are congruent] ∴ arc PR and arc RQ are congruent to arc PS.
Solution & Step-by-Step Answer:
i. Seg MN is the diameter of the circle. … [Given] ∴ m∠AOM + m∠AON = 180° … [Angles in a linear pair] ∴ m∠AOM + (m∠AOB + m∠BON) = 180° … [Angle addition property] ∴ 100° + m∠AOB + 35° = 180° …[∵ m∠AOM = 100°, m∠BON = 35°] ∴ m∠AOB + 135° = 180° ∴ m∠AOB = 180°- 135° ∴m∠AOB = 45° …(i) Also, m∠DOM + m∠DON = 180° … [Angles in a linear pair] ∴ m∠DOM + (m∠COD + m∠CON) = 180° … [Angle addition property] ∴ 100° +m∠COD + 35°= 180° …[∵ m∠DOM = 100°, m∠CON = 35° ] ∴ m∠COD + 135° = 180° ∴ m∠COD = 180°- 135° ∴ m∠COD = 45° …(ii)
ii. m(arc AB) = m∠AOB = 45° … [From (i)]
m(arc DC) = m∠DOC = 45°...[From (ii)]
∴ m(arc AB) = m(arc DC) …[From (i) and (ii)]
∴ arc AB ≅ arc CD
… [If the measures of two arcs of a circle are same, then the two arcs are congruent]
iii. arc AB ≅ arc CD
∴ chord AB ≅ chord CD ….[The chords corresponding to congruent arcs are congruent]
Maharashtra Board Class 8 Maths Chapter 17 Circle: Chord and Arc Practice Set 17.2 Intext Questions and Activities
Solution & Step-by-Step Answer:
[Students should attempt the above activities on their own.]
Solution & Step-by-Step Answer:
[Students should attempt the above activities on their own.]
ii. a. Draw a circle with centre C.
b. Draw the congruent chords AB and DE of the circle. Draw the radii CA, CB, CD and CE.
c. Check that ∠ACB and ∠DCE are congruent.
d. Hence show that measure of arc AB and arc DE is equal. Hence these arcs are congruent. (Textbook pg. no. 117)
Solution:
[Students should attempt the above activities on their own.]