Reduce number of operations in `Triangle::circumscribed_circle` #688

Job	Run time
cargo fmt	25s
cargo clippy (wasm32)	43s
cargo test (windows-latest)	44s
cargo clippy (windows-latest)	1m 22s
cargo test (macos-latest)	36s
cargo check (msrv) (windows-latest)	57s
cargo clippy (macos-latest)	43s
cargo test (ubuntu-latest)	19s
cargo check (msrv) (wasm32)	23s
cargo check (msrv) (macos-latest)	33s
cargo clippy (ubuntu-latest)	45s
cargo check (msrv) (ubuntu-latest)	31s
cargo doc	19s
typos	5s
cargo test (wasm32)	36s
	9m 1s

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