1) Because
is a central angle,
.
Since
and
are supplementary, they form a linear pair, and thus
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5) Tangents drawn from an external common point are congruent, so CR=CP=8 and RB=BQ=4. This means that QA=11, and so PA=11 as well. Adding CP+PA, we get AC=19.
6) By the inscribed angle theorem, angle QPR measures 36 degrees.