Understand concept of Using the Pythagorean Identity (SinA)^2 + (CosA)^2 = 1. This is one of the Trigonometric Identities that are used to solve real world problems. RELATED LESSONS: (1). Use the Pythagorean Identity to determine signs of the Trig Functions. • Use the Pythagorean Identity to determine ... (2). Using the Trigonometric Identities to determine Angles in the Quadrant III. • Using the Trigonometric Identities to dete... (3). Concept of Using the Pythagorean Identity (SinA)^2 + (CosA)^2 = 1 • Concept of Using the Pythagorean Identity ... (4). Use Pythagorean / Trigonometric Identity for an angle in the Quadrant II • Use Pythagorean / Trigonometric Identity f...