Figure 4. A unit circle illustrating signs of trigonometric ratios in the four quadrants using an acronym - ASTC

From

Designing a Theoretical Proposal Using Problem – Based Learning to Improve Learning of Trigonometric Ratios among Grade Eleven Students

Matías Arce Sánchez, Cristina Pecharromán Gómez, Tomás Ortega del Rincón, Thomas Mwenya Musonda

American Journal of Educational Research. 2023, 11(2), 53-78 doi:10.12691/education-11-2-5