Reduce number of operations in `Triangle::circumscribed_circle` #668

Job	Run time
cargo clippy (wasm32)	40s
cargo check (msrv) (windows-latest)	48s
cargo check (msrv) (wasm32)	33s
cargo check (msrv) (macos-latest)	28s
cargo doc	24s
cargo check (msrv) (ubuntu-latest)	29s
cargo clippy (windows-latest)	1m 17s
cargo fmt	25s
cargo clippy (macos-latest)	54s
cargo clippy (ubuntu-latest)	44s
cargo test (windows-latest)	53s
cargo test (wasm32)	20s
cargo test (macos-latest)	22s
typos	4s
cargo test (ubuntu-latest)	19s
	8m 40s

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