Swing two hinged sides until their tips meet — or show they never can — then bound the third side with reach-arcs and count how many triangles an angle-side-side condition really fits.
Side a lies on the baseline and sides b and c are hinged at its ends: the player drags each tip so the sides sweep, and too-short sides visibly fail to meet even at full stretch — that gap is the triangle inequality. A second mode dials the third side while two reach-arcs cross, kiss or miss, pinning down |a − b| < c < a + b; a third fixes an angle and one side and swings the other, so the circle of possible positions meets the ray 0, 1 or 2 times and every landing must be found. It drills 7.G.2 — when given conditions determine a unique triangle, more than one, or none — and targets the belief that any three lengths make a triangle. Best for Grade 7.
A free, no-signup, no-ads math game for Grade 7 — practising triangle-inequality, triangle-construction, unique-triangle, sss, ssa. Play in your browser on the KidsDoMath games hub or explore more Geometry & Shapes games.
By grade level: 7th Grade Math Games
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What math does Triangle Builder practice? Triangle Builder practices Triangle Inequality, Triangle Construction, Unique Triangle, Sss. Side a lies on the baseline and sides b and c are hinged at its ends: the player drags each tip so the sides sweep, and too-short sides visibly fail to meet even at full stretch — that gap is the triangle inequality.
What grade is Triangle Builder for? Triangle Builder is built for Grade 7 (ages 12–13). It sits in the Geometry & Shapes strand, and it ramps across 8 levels so younger or older players find their own pace.
How do you play Triangle Builder? Swing two hinged sides until their tips meet — or show they never can — then bound the third side with reach-arcs and count how many triangles an angle-side-side condition really fits.
Is Triangle Builder free to play? Yes. Triangle Builder is free, with no ads and no sign-up, and it runs in the browser on a phone, tablet or computer.