Author Topic: Trig function question (Read 652 times) Tweet Share

preliminary17hsc18 · « **on:** May 01, 2018, 11:28:07 am »

Hi,
Just need help with a question

Find the equation of the tangent to the curve y = sin3x at the point (pi/4, 1/root-2)
Thanks!

RuiAce · « **Reply #1 on:** May 01, 2018, 11:38:01 am »

Quote from: preliminary17hsc18 on May 01, 2018, 11:28:07 am

Hi,
Just need help with a question
Find the equation of the tangent to the curve y = sin3x at the point (pi/4, 1/root-2)
Thanks!

$y=\sin 3x \implies \frac{dy}{dx} = 3\cos 3x.$
$\text{At }x = \frac\pi4, \frac{dy}{dx} = -\frac{3}{\sqrt{2}}.$
$\text{So the tangent is }y - \frac{1}{\sqrt2} = -\frac{3}{\sqrt2} \left( x - \frac\pi4\right)\\ \text{which you can then rearrange.}$

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Author Topic: Trig function question (Read 652 times) Tweet Share

preliminary17hsc18

Trig function question

RuiAce

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