How could you rewrite the hypotenuse in terms of $\cos$ and $\sin$??
$$ \frac{\sin \theta}{\cos \theta} $$
Because of Pythagoras, what could you write??
$$ \sin^2\theta + \cos^2\theta = 1 $$
How could you simplify $7(1 - \cos^2\theta)$??
$$ 7\sin^2\theta $$
How could you rewrite $(\cos^4\theta - \sin^4\theta)$ as the difference of two squares??
$$ (\cos^2\theta - \sin^2\theta)(\cos^2\theta + \sin^2\theta) $$
How could you simplify $(\cos^2\theta - \sin^2\theta)(\cos^2\theta + \sin^2\theta)$??
$$ (\cos^2\theta - \sin^2\theta) $$
How could you rewrite $3\sin\theta - 2\cos\theta = 0$??
$$ \tan\theta = \frac{2}{3} $$
What is the formula for $\sin(A \pm B)$??
$$ \sinA\cosB \pm \cosA\sinB $$
What is the formula for $\cos(A \pm B)$??
$$ \cosA\cosB \mp \sinA\sinB $$
What is the formula for $\tan(A \pm B)$??
$$ \frac{\tanA \pm \tanB}{1 \mp \tanA\tanB} $$
What is the formula for $\sin2A$??
$$ 2\sinA\cos A $$
What is the formula for $\cos2A$??
$$ 2\cos^2 A - 1 $$
What is the formula for $\tan2A$??
$$ \frac{2\tan\A}{1-\tan^2 A} $$
2021-11-09
What are the three formulas for $\cos 2\theta$??
$$ \cos^2 \theta - \sin^2 \theta $$ $$ 2\cos^2 \theta - 1 $$ $$ 1-2\sin^2 \theta $$
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date: 2020-11-30 13:10
tags:
- '@?maths'
- '@?public'
- '@?further-maths'
title: Maths - Trigonometry Identities