In the following figure find ZCOD, given LAOB = 125°
Answers
Answer:
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Step-by-step explanation:
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Answer:
Given−
AB,BC,CD & AD are tangents drawn from the points
A,B,C to the circle with centre O.
OA,OB,OC & OD are the lines joining O with
A,B,C & D respectively.
∠AOB = 125 °
To find out−
∠DOC=?
Step by step explanation :
AB & AD are tangents drawn from the point
A to the circle with centre O.
OA is the line joining O with A.
∴∠OAB = ∠OAD .....(i)
Similarly it can be shown that
∠OBA = ∠OBC ........(ii),
∴From (i) & (ii) ∠OAB+∠OBA=∠OAD+∠OBC .....(iii)
Similarly ∠ODA = ∠ODC & ∠OCB = ∠OCD
∴∠ODA+∠OCB = ∠ODC+∠OCD
i.e ∠ODC+∠OCD = 1/2(∠ADC+BCD) ........(iv)
Again∠AOB=125° ⟹∠OAB+∠OBA = 180°−125° = 55°
(sum of the ∠s of a Δ=180°)
and ∠AOB = 125°⟹reflex∠AOB = −360°−125° = 235° ...(v)
Now AOBCD is a pentagon.
∴reflex ∠AOB+(∠OAD+∠OBC)+(∠ADC+BCD) = 540°
(sum of the angles of a pentagon)
⟹235° +55°+2(∠ODC+∠OCD) = 540° (using iii,iv,v)
⟹∠ODC +∠OCD =125°
⟹∠COD=180° −125° = 55°