Reduce number of operations in `Triangle::circumscribed_circle` #687

Job	Run time
cargo clippy (windows-latest)	1m 17s
cargo clippy (macos-latest)	1m 0s
cargo check (msrv) (wasm32)	20s
cargo clippy (wasm32)	40s
cargo clippy (ubuntu-latest)	47s
cargo check (msrv) (windows-latest)	45s
cargo check (msrv) (macos-latest)	31s
cargo doc	30s
cargo check (msrv) (ubuntu-latest)	24s
cargo fmt	20s
cargo test (windows-latest)	1m 8s
cargo test (macos-latest)	30s
cargo test (wasm32)	21s
typos	4s
cargo test (ubuntu-latest)	22s
	8m 59s

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