Maths Puzzle

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Across
  1. 4. The other name for x-coordinate.
  2. 6. The line segment connecting two non-adjacent sidesof a polygon.
  3. 8. A 3 sided polygon.
Down
  1. 1. The horizontal axis in cartesian coordinate plane.
  2. 2. A selection in which order is not important.
  3. 3. Mathematician famous for "Elements of geometry"
  4. 5. A line that intersects the circle at any one point.
  5. 7. The union of two rays with a common end-point,called the vertex.