G.78 right, obtuse, and acute-angled triangles — Heath

I.def.21

Further, of trilateral figures, a right-angled triangle is that which has a right angle, an obtuse-angled triangle that which has an obtuse angle, and an acute-angled triangle that which has its three angles acute.

Dependency Graph

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Required for

G.79, G.80, G.91, G.92, G.93, G.94, G.95, G.97, G.114, G.116, G.143, G.144, G.145, G.162, G.163, G.164, G.218, G.223, G.237, G.240, G.241, G.243, G.244, G.385, G.390, G.396, G.397, G.398, G.399, G.400, G.401, G.402, G.403, G.404, G.405, G.406, G.407, G.408, G.409, G.410, G.411, G.412, G.413, G.414, G.415, G.416, G.417, G.418, G.419, G.420, G.421, G.423, G.425, G.427, G.431, G.433, G.434, G.435, G.436, G.437, G.438, G.439, G.440, G.441, G.442, G.443, G.444, G.445, G.446, G.447, G.448, G.449, G.450, G.451, G.452, G.453, G.457, G.458, G.459, G.460, G.461, G.462, G.463, G.464, G.465, G.466, G.467, G.468, G.470, G.472, G.474, G.476, G.477, G.478, G.479, G.480, G.481, G.482, G.483, G.484, G.485, G.486, G.487, G.488, G.489, G.490, G.491, G.492, G.493, G.494, G.495, G.496, G.497, G.498, G.499, G.500, G.528, G.545, G.546, G.561, G.563, G.565, G.570, G.571, G.572, G.573, G.577, G.578, G.584, G.589, G.590, G.592, G.594, G.595, G.597, G.600, G.601