Write the Word or Phrase That Best Completes Each Statement $$\text { Discuss the graph of the equation } \frac { x ^ { 2 } } { a ^ { 2 } } + \frac { y ^ { 2 } } { b ^ { 2 } } = 1 \text { if } a = b \text {. }$$

Write the word or phrase that best completes each statement or answers the question.
- $$\text { Discuss the graph of the equation } \frac { x ^ { 2 } } { a ^ { 2 } } + \frac { y ^ { 2 } } { b ^ { 2 } } = 1 \text { if } a = b \text {. }$$