Please solve q 9 ?

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1 Answer
CW
May 6, 2018

angleBDE=30^@∠BDE=30∘

Explanation:

enter image source here
As shown in the figure, ABCDABCD is a square. Two circles with center at B and CBandC, respectively, meet at EE,
let rr be the side of the square and the radius of the circles,
=> BE=BC=CE=r⇒BE=BC=CE=r,
=> DeltaBEC is equilateral,
=> angleBCE=60^@,
recall that the angle subtended by an arc at the center of a circle is twice the angle subtended by the same arc at the circumference,
=> angleBCE=2*angleBDE,
=> angleBDE=(angleBCE)/2=60/2=30^@

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