Points A, D, C, B and E are concyclic. If $$\angle$$AEC = 50$$^\circ$$ and $$\angle$$ABD = 30$$^\circ$$, then what is the measure(in degrees) of $$\angle$$CBD?
ADCE is a cyclic quadrilateral, so opposite angles are supplementary.
$$\Rightarrow$$Â Â $$\angle$$ADC +Â $$\angle$$AEC = 180$$^\circ$$
$$\Rightarrow$$Â Â $$\angle$$ADC +Â 50$$^\circ$$ = 180$$^\circ$$
$$\Rightarrow$$Â Â $$\angle$$ADC =Â 130$$^\circ$$
ABCD is a cyclic quadrilateral, so opposite angles are supplementary.
$$\Rightarrow$$ $$\angle$$ABC + $$\angle$$ADC = 180$$^\circ$$
$$\Rightarrow$$ x +Â 30$$^\circ$$ + 130$$^\circ$$ = 180$$^\circ$$
$$\Rightarrow$$ x = 20$$^\circ$$
$$\Rightarrow$$Â Â $$\angle$$CBD = x =Â 20$$^\circ$$
Hence, the correct answer is Option A
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