Question

Please help me with the 11th one.....

Answer 1

Answer:

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Answer 2

The length of side DC would also be same (due to symmetry) or we can say that the angle intended by the diameters AC and BD at O are same therefore the length of DC would be 7cm....

Similarly due to the above reason it can be said that All the angles A B C and D are equal or.... we can calculate:

sum of angles in a triangle is 180

both the lines AO and BO are radii so the triangle is isoceles

$180 - 72 - 72 = 36$

This is angle OAB and as AC and BD are straight lines the angle COD is also 36 ...