• TheGrandNagus@lemmy.world
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    28 days ago

    What a deviously misleading diagram.

    The triangle on the left isn’t actually a right angle triangle, as the other angles add to 100°, meaning the final one is actually 80°, not 90°.

    Therefore the triangle on the right also isn’t a right angle triangle. That corner is 100°.

    100+35=135°. 180-135=45°. So that’s 45° for the top angle.

    X = the straight line of the joined triangles (180°) - the top angle of the right triangle (45°). 180-45=135°

    X is 135°, not the 125° it initially appears to be.

    • PM_Your_Nudes_Please@lemmy.world
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      26 days ago

      The triangles aren’t drawn to scale. The middle line isn’t a 90° angle, because it isn’t specifically marked with a square angle in the corner. Triangles always add up to 180°, so the angle in the left triangle is actually 80°, not 90°.

    • PM_Your_Nudes_Please@lemmy.world
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      26 days ago

      Nah, the angle isn’t specified as a right angle. We can’t assume it’s 90° just because it’s drawn that way, because it isn’t drawn to scale.

      Left triangle has 180° total. 60+40=100, which means that middle line is actually 80°, not 90. And since the opposite side is the inverse, we know it is 100° on the other side.

      100+35=135. We know the right triangle also has 180° total, so to find the top corner we do 180-135=45. So that top corner of the right triangle is 45°, meaning x must be 135° on the opposite side.