Hello

1. / An angle measuring exactly 90 degrees, like in a right triangle.
5. / A line drawn from a triangle vertex to the opposite side's midpoint, also the points that are equally far from two sides.
6. / A line connecting two sides' midpoints in a triangle, always parallel to the third side and half its length.
9. / An angle measuring more than 90 but less than 180 degrees in shapes like obtuse triangles and trapezoids.
11. angle / An angle formed by extending a polygon's side to a line that passes through an adjacent side.
15. / A triangle with no equal sides, and also can have no equal angles.
16. / A math function for solving problems with angles and distances in right triangles, comparing the opposite side to the adjacent side.

2. / A branch of math dealing with triangles, their sides and angles, and used in many fields like engineering, physics, and astronomy.
3. / A point halfway between two endpoints of a line segment, and a formula to find its coordinates.
4. / A math function for solving problems with angles and distances in right triangles, comparing the opposite side to the hypotenuse.
7. angle / An angle inside a polygon that's less than 180 degrees, and a polygon's total interior angles equal (n-2) times 180 degrees.
8. / An angle less than 90 degrees found in shapes like acute triangles and trapezoids.
10. / A three-sided shape with interior angles adding up to 180 degrees.
12. / A four-sided shape, and a rectangle is a type with four right angles.
13. / A math function that helps solve problems with angles and distances in right triangles by comparing the adjacent side to the hypotenuse.
14. / A shape with five sides, and a regular one has equal side lengths and angles.