If a right triangle is also an [color=#000000][b]isosceles triangle[/b][/color], its [color=#000000][b]legs are equal in length [/b][/color](by definition of an isosceles triangle.) Its [color=#ff00ff][b]2 acute angles are equal[/b][/color] (by the Isosceles Triangle Theorem), and thus [color=#ff00ff][b]each one measures 45 degrees.[/b][/color] (Notice how [color=#ff00ff][b]two 45-degree angles[/b][/color] fit inside the interior angle that measures [b]90 degrees[/b].)