Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Prove the identity.\newline sin2x1+cos2x=tanx\frac{\sin 2x}{1+\cos 2x}=\tan x

Full solution

Q. Prove the identity.\newline sin2x1+cos2x=tanx\frac{\sin 2x}{1+\cos 2x}=\tan x
  1. Apply Double Angle Formulas: We will start by using the double angle formulas for sine and cosine. The double angle formula for sine is sin2x=2sinxcosx\sin 2x = 2 \sin x \cos x, and for cosine is cos2x=cos2xsin2x\cos 2x = \cos^2 x - \sin^2 x. We will apply these formulas to the left side of the identity.
  2. Rewrite sin2x\sin 2x: Rewrite sin2x\sin 2x using the double angle formula:\newlinesin2x=2sinxcosx\sin 2x = 2 \sin x \cos x.
  3. Rewrite 1+cos2x1 + \cos 2x: Rewrite 1+cos2x1 + \cos 2x using the double angle formula and the Pythagorean identity sin2x+cos2x=1\sin^2 x + \cos^2 x = 1:1+cos2x=1+(cos2xsin2x)=(1sin2x)+cos2x=cos2x+sin2x1 + \cos 2x = 1 + (\cos^2 x - \sin^2 x) = (1 - \sin^2 x) + \cos^2 x = \cos^2 x + \sin^2 x.
  4. Substitute into Identity: Now, we substitute the expressions we found into the left side of the identity: sin2x1+cos2x=2sinxcosxcos2x+sin2x\frac{\sin 2x}{1 + \cos 2x} = \frac{2 \sin x \cos x}{\cos^2 x + \sin^2 x}.
  5. Simplify Denominator: Since cos2x+sin2x=1\cos^2 x + \sin^2 x = 1, we can simplify the denominator:\newline$(\(2\) \sin x \cos x) / (\cos^\(2\) x + \sin^\(2\) x) = (\(2\) \sin x \cos x) / \(1\) = \(2\) \sin x \cos x.
  6. Divide by \(\cos x\): Now, we divide both the numerator and the denominator by \(\cos x\), assuming \(\cos x \neq 0\) (since division by zero is undefined):\[\frac{2 \sin x \cos x}{\cos x} = 2 \sin x.\]
  7. Correct Mistake: We realize there is a mistake in the previous step. We should have divided by \(\cos^2 x\), not \(\cos x\). Let's correct this:\(\newline\)\[(2 \sin x \cos x) / \cos^2 x = (2 \sin x) / \cos x.\]

More problems from Find derivatives of other trigonometric functions