Question

Sin A + Cos A / Sin A - Cos A - Sin A - Cos A / Sin A + Cos A = 4 / Tan A - Cot A​

Answer 1

Take an x-axis and an y-axis (orthonormal) and let O be the origin. A circle centered in O and with radius = 1 is known as trigonometric circle or unit circle.

If P is a point from the circle and A is the angle between PO and x axis then:

the x-coordinate of P is called the cosine of A. We write cos(A) or cos A;

the y-coordinate of P is called the sine of A. We write sin(A) or sin A;

the number sin(A)/cos(A) is called the tangent of A. We write tan(A) or tan A;

the number cos(A)/sin(A) is called the cotangent of A. We write cot(A) or cot A.