Radians: Radians are a unit of measurement for angles. They represent the distance traveled along the circumference of a circle divided by its radius. Unlike degrees, which divide a circle into 360 equal parts, radians divide it into approximately 6.28 equal parts.
Power Rule: The power rule is a fundamental rule in calculus used to find derivatives. It states that if f(x) = x^n, where n is any real number (except -1), then the derivative of f(x) with respect to x is given by f'(x) = nx^(n-1).
Trigonometric Identities: Trigonometric identities are equations involving trigonometric functions that hold true for all values of the variables involved. These identities help simplify expressions and solve equations involving trigonometric functions. Examples include Pythagorean identities like sin^2(x) + cos^2(x) = 1 and double-angle formulas like sin(2x) = 2sin(x)cos(x).