In the given circle with center o, ∠ABC=100°, ∠ACD=40° and CT is tangent to the circle at C. find ∠ADC and ∠DCT.
In a cyclic quadrilateral ABCD,
`∠ ABC+∠ADC=180°` (Opposite angle of a cydic quadrilateral are supplementary)
Now, in `ΔACD`,
`"Now" ∠DCT=∠CAD ...........("angles in the alternate segment are equal")`