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In the Given Circle with Center O, ∠Abc=100°, ∠Acd=40° and Ct is Tangent to the Circle at C. Find ∠Adc and ∠Dct. - Mathematics

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Question

In the given circle with center o, ∠ABC=100°, ∠ACD=40° and CT is tangent to the circle at C. find ∠ADC and ∠DCT. 

 

Sum

Solution

In a cyclic  quadrilateral ABCD, 

`∠ ABC+∠ADC=180°`   (Opposite angle of a cydic quadrilateral are supplementary)

`⇒ 100°+∠ADC=180°`

`⇒ ∠ADC=80°`

Now, in `ΔACD`,

`∠ADC+∠CAD+∠ADC=180°`

`⇒40°+∠CAD+80°=180°`

`⇒∠CAD=180°-120°`

`⇒∠CAD=60°`

`"Now" ∠DCT=∠CAD ...........("angles in the alternate segment are equal")`

`∴ ∠DCT=60°`

 

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Chapter 18: Tangents and Intersecting Chords - Exercise 18 (C) [Page 288]

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Selina Mathematics [English] Class 10 ICSE
Chapter 18 Tangents and Intersecting Chords
Exercise 18 (C) | Q 42 | Page 288
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