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secondary 4 | E Maths
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How to do q4 !! Thanks for help in advance!!
Date Posted: 5 years ago
Views: 290
∠COB = ∠BAO + ∠ABO (ext angle = sum of 2 int opp angles)
= 90° + x°
OB = OC (both are radius of the same cir cle)
Since D is midpoint of BC,
BD = CD
OD is common to △BOD and △ COD
So △ BOD and △COD are congruent (SSS)
So ∠BOD = ∠ COD
∠COB = ∠COD + ∠COB
(90 + x)° = 2∠COD (since ∠BOD = ∠ COD)
∠COD = (90 + x)° ÷ 2
= (45 + ½x)°
= 90° + x°
OB = OC (both are radius of the same cir cle)
Since D is midpoint of BC,
BD = CD
OD is common to △BOD and △ COD
So △ BOD and △COD are congruent (SSS)
So ∠BOD = ∠ COD
∠COB = ∠COD + ∠COB
(90 + x)° = 2∠COD (since ∠BOD = ∠ COD)
∠COD = (90 + x)° ÷ 2
= (45 + ½x)°
Thanks
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The challenge in this question is to express the angles in terms of x. So essentially, you are finding the answer in terms of x rather than regular numbers. Usual rules for circles and triangles continue to apply.
Date Posted:
5 years ago
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