Understanding elementary shapes

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Across
  1. 3. a triangle having two equal sides
  2. 8. a triangle having all three unequal sides
  3. 10. a triangle in which each angle is less than 90
  4. 11. one complete revolution
  5. 12. an angle whose measure is 90
Down
  1. 1. shape of a ball
  2. 2. a triangle in which any one angle is greater than 90
  3. 4. half a revolution
  4. 5. shape of a playing die
  5. 6. an angle whose measure is smaller than that of right angle
  6. 7. a triangle in which any one angle is right angle
  7. 9. a triangle having three equal sides