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In the given figure ‘O’ is the centre of the circle.Arc AB = Arc BC= Arc CDIf ∠OAB = 48 °, Find:i)∠AOB ii) ∠BOD iii) ∠OBD |
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Answer» Answer: Let AB be the chord of the given circle with centre O and a radius of 5 cm.Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, DRAW OM perpendicular to AB.Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmLet AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2⇒ MB2 = (25 − 9) = 16Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2⇒ MB2 = (25 − 9) = 16⇒ MB=16 −−−√cm=4 cmLet AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2⇒ MB2 = (25 − 9) = 16⇒ MB=16 −−−√cm=4 cmSince the perpendicular from the centre of a circle to a chord bisects the chord, we have:Let AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2⇒ MB2 = (25 − 9) = 16⇒ MB=16 −−−√cm=4 cmSince the perpendicular from the centre of a circle to a chord bisects the chord, we have:AB = 2 × MB = (2 × 4) cm = 8 cmLet AB be the chord of the given circle with centre O and a radius of 5 cm.From O, draw OM perpendicular to AB.Then OM = 3 cm and OB = 5 cmFrom the right ΔOMB, we have:OB2 = OM2 + MB2 (Pythagoras theorem)⇒ 52 = 32 + MB2⇒ 25 = 9 + MB2⇒ MB2 = (25 − 9) = 16⇒ MB=16 −−−√cm=4 cmSince the perpendicular from the centre of a circle to a chord bisects the chord, we have:AB = 2 × MB = (2 × 4) cm = 8 cmHence, the required LENGTH of the chord is 8 cm. |
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