Extra, focused practice with complete two-column proofs about segments and angles. Every proof here is a complete proof that ends at the statement it was asked to prove. No proof here hands you a number or asks you for one — every Given and every Prove is a statement about the figure itself: a congruence, a midpoint, a bisector, a pair of angles. The only numbers that ever appear are 90 and 180, where a right angle or a straight angle calls for them. Proofs run from 3 steps up to 10. Work one proof at a time: fill every blank — by choosing from a drop-down list, or by dragging statement and reason chips into the empty rows — then press Check Proof.
Two things to know about how checking works. First, order matters where the logic says it does: some lines of a proof can trade places and the proof is still correct, and the checker accepts those trades — but a line that uses a fact you have not established yet (a conclusion placed before the steps it rests on, for example) will be marked wrong even if the statement and reason match each other. Second, a correct row turns green and locks; a wrong row earns a hint and another try. Shorter proofs give you 2 checks before a stuck row is filled in and marked as shown; longer proofs give you 3. A row that was shown is not a row you earned, and the completion message says so.
These proofs are short — three to five lines — and every one ends at the statement it was asked to prove. The first proof is the on-ramp: its lists only offer reasons from that proof's own world. From the second proof on, the lists also include reasons that do not belong — part of the work is leaving those alone.
These proofs run longer — five to ten lines — because the equalities have to be built, step by step, before the final statement can be reached. Every proof still ends at the statement it was asked to prove. This section also has a Build the Whole Proof, where the table starts empty. You get 3 checks per proof before a stuck row is shown.
Segment and Angle Proofs — Mr. J Geometry. All activities on this page run entirely in your browser.