Page 4 - Activity 3 Opposite angles of Cyclic Quadrilateral Ch.10 Circle
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5. Make the cut outs of the angles, (i.e. ∠A, ∠B, ∠C and ∠D) with the help of a
transparent sheet, (see Fig. 25.6)
6. By using adhesive, paste cut outs of the opposite angles ∠A and ∠C, ∠B and ∠D.
(see Fig. 25.7)
Demonstration
Joining the opposite angles ∠A and ∠C, ∠B and ∠D, we get straight angles, (see Fig.
25.4)
Hence, ∠A + ∠C = 180° and ∠B + ∠D = 180°.
Observation
By actual measurement, ∠A = ……… , ∠B = ……… ,
∠C = ……… , ∠D = ……… ,
So, ∠A + ∠C = ……… , ∠B + ∠D = ……… .
Hence, sum of each pair of the opposite angles of a cyclic quadrilateral is ……… .
Result
We have verified that the opposite angles of a cyclic quadrilateral are always
supplementary.
Application
This property can be used in solving various problems in geometry.
Viva Voce
Question 1:
What do you understand by the term a cyclic quadrilateral?
Answer:
