Question

ABCD is a cyclic quadrilateral if angleBCD= 100 and angleABD = 70 find angle ADB​

Answer 1

Answer:ADB = 30

for acyclic quadrilateral sum of opposite angles = 180

so BCD + BAD = 180

     100 + BAD = 180

      BAD = 80

ABD = 70

BAD = 80

THEN ADB = 180 - 70 + 80

          ADB = 30

sum of  all angles of a triangle = 180

so ADB IS ATRIANGLE

Answer 2

Question:

ABCD is a cyclic quadrilateral. If <BCD = 100°

and <ABD = 70° .Find <ADB

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Solution :

• In cyclic quadrilateral ABCD,

$\tt { \angle BCD + \angle DAB = 180°}$(opposites angles of cyclic quadrilateral )

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$: \implies \tt { 100° + \angle DAB = 180°}$

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$: \implies \tt { \angle DAB = 80°}$

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Now, In triangle DAB:

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$\tt { \angle DAB + \angle ABD + \angle ADB = 180°}$

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$: \implies \tt { 80° + 70° + \angle ADB = 180°}$

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$: \implies \tt { \angle ADB = 30°}$