Final answer:
The question is asking for a missing statement in a geometric proof involving a triangle with a right angle. The statement likely involves the properties of a right triangle or the sum of angles in a triangle.
Step-by-step explanation:
The question seems to be related to a mathematical proof involving angles in a triangle, specifically a right angle (90°). It's not entirely clear which proof or theorem is being referenced as the details are not fully provided. However, based on the given information, the missing statement could be related to the properties of a right triangle or the sum of angles in a triangle, which is always 180°.
In geometric proofs, once we establish that m∠ is 90°, the other two angles must sum to 90° as well because the sum of angles in any triangle is 180°. If the proof is aimed at establishing a relationship between the sides of the triangle, we might use the Pythagorean theorem or trigonometric ratios such as sine, cosine, or tangent. However, without more context it is difficult to determine the exact missing statement.