The triangle inequality for real numbers is $ |a+b| \le |a| + |b|$ in which […]
Category: Trigonometry
Christina DanielDo the angle addition identities only work for positive angles?
The Angle Addition Identities were derived using $\sin\theta \equiv \frac{opp}{hyp}$ and $\cos\theta \equiv \frac{adj}{hyp}$. In addition, $\theta$ […]
The Pythagorean Theorem and the Unit Circle
This following diagram shows that $\displaystyle \sin^2 \theta + \cos^2 \theta = 1$, given $ […]
Double Angle Formulas
In the Angle Addition Identities post it was shown that $ \displaystyle \sin(x+y) = \sin x \cos […]