14. All phone numbers consist of a three-digit area code, a three-digit exchange, and then a four-digit number. A town uses the 587 area code and the exchange 355; for example, 587-355-1234. How many different phone numbers are possible in this town under the following conditions?

a) At least one digit repeats in the last four digits of the phone number.

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq

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step-by-step explanation:

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