Across
- 3. two angles or arcs. Whose sum is 180 degrees.
- 6. In classical geometry, a radius of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin radius, meaning ray but also the spoke of a chariot wheel.
- 7. Having the three sides. Of unequal length.
- 9. the line segment joining two points on a curve. The term is often used to describe a line segment whose ends lie on a circle.
- 11. Spherical geometry is the geometry of the two-dimensional surface of a sphere. In this context the word "sphere" refers only to the 2-dimensional surface and other terms like "ball" or "solid sphere" are used for the surface together with its 3-dimensional interior.
- 14. Basic element of Euclidean geometry. Euclid defined a line as an interval between two points and claimed it could be extended indefinitely in either direction
- 16. a triangle that has two sides of equal length. Sometimes it is specified as having exactly two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case.
- 18. lines that intersect at a right angle. Which is 90 degrees.
- 19. In geometry, perimeter refers to the boundary of a closed plane figure. You might remember calculating perimeters in school. If each side of an equilateral triangle measures 9 feet, then the perimeter of the triangle measures 27 feet.
- 20. the set of all points in the plane that are a fixed distance (the radius) from a fixed point (the centre). Any interval joining a point on the circle to the centre is called a radius. By the definition of a circle, any two radii have the same length.
- 22. the amount of space in a certain 3D object. For instance, a fish tank has 3 feet in length, 1 foot in width and two feet in height.
- 23. often denoted by letters such as P, Q, R, S, is a point where two or more curves, lines, or edges meet. As a consequence of this definition, the point where two lines meet to form an angle and the corners of polygons and polyhedra are vertices.
Down
- 1. It has no size i.e. no width, no length and no depth. It is shown by a dot.
- 2. the amount of space within the perimeter of a 2D shape. It is measured in square units, such as cm², m², etc.
- 4. In geometry, parallel lines are coplanar straight lines that do not intersect at any point. Parallel planes are planes in the same three-dimensional space that never meet.
- 5. an angle exceeding 90 degrees but less than 180 degrees. But more than 0 degrees.
- 8. In geometry, the circumference is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle
- 10. In geometry, a ray can be defined as a part of a line that has a fixed starting point but no endpoint. It can extend infinitely in one direction.
- 12. a four-sided polygon, having four edges and four corners. The word is derived from the Latin words quadri, a variant of four, and latus, meaning "side"
- 13. a polyhedron comprising an n-sided polygon base, a second base which is a translated copy of the first, and n other faces, necessarily all parallelograms, joining corresponding sides of the two bases. All cross-sections parallel to the bases are translations of the bases.
- 15. a polyhedron. which the base is a polygon and all lateral faces are triangles.
- 17. an angle exceeding 90 degrees. But less than 180 degrees
- 21. the surface traced by a moving straight line (the generatrix) that always passes through a fixed point (the vertex). The path, to be definite, is directed by some closed plane curve (the directrix), along which the line always glides.