MATHEMAGICA (ROUND 1)

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Across
  1. 2. Name of the symbol φ.
  2. 3. A matrix is not invertible if it's determinant is _______.
  3. 4. Name of mathematician who gave the mathematical constant "e".
  4. 6. Collection of objects when not considered in order.
  5. 7. If a + bi = z, then a - bi is called as complex _______.
Down
  1. 1. For which geometric figure, equation x² + y² + z² = 1 holds?
  2. 5. Unit for measuring angles of a circle.