# Math Help - Gradient of Normal

1. ## Gradient of Normal

What is the gradient of the normal y= 3cos2x where y = 1.5 ??

2. Originally Posted by nath_quam
What is the gradient of the normal y= 3cos2x where y = 1.5 ??
$y = 3cos2x$
$1.5=3cos2x$
$cos2x= .5$
Gradient of tangent= $\frac{dy}{dx}=-6sin2x=-6*\sqrt{3}/2$
Gradient of normal= $\frac{-1}{gradient of tangent}=\frac{1}{3\sqrt{3}}$
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