Never mind, it appears the downvote has to do with differences of opinion about mathematical style (or at least one comment implies such). And another downvote appeared for good measure. It is sad that some folks downvote insightful answers based on nonmathematical matters like such.

[ SmokeDetector | MS ] Bad keyword in answer, blacklisted website in answer, pattern-matching website in answer, potentially bad ip for hostname in answer, potentially bad keyword in answer, +1 more (261): How to find measurements of angle CBD? by connieurford on math.SE

D1, D2, D3.

D4, D5, D6.

D7, D8, D9.

D10, D11, D12.

D13, D14, D15.

C1, C2, C3.

C4, C5, C6.

C7, C8, C9.

C10, C11, C12.