To find the derivatve of the square root of cos x:
Use the chain rule; this means multiply the inner derivative by the outer derivative.
You can write the question f(x) = (cos x)1/2
This general break-down explains how to find d/dx f(x)
note: d/dx basically symbolizes "the derivative of"
In general terms:
f(x) = x1/2
g(x) = cos x
f(g(x)) = (cos x)1/2
outer derivative: d/dx f(z) = (1/2)*x-1/2 = 1/(4cos x)1/2
inner derivative: d/dx g(x) = -sin(x)
final answer: d/dx f(g(x)) = -sin(x)/(4*cos x)1/2
note: d/dx means "the derivative of"; so d/dx x = 1
Further explained:
Set up the equation to a more general form: (cos x)1/2
To make the inner derivative, look at cos(x)
To make the outer derivative, look at x1/2
note: x ~ cos x; so we treat (cos x) simply as x, to create the outer derivative
You probably know the necessary derivates:
1. derivative of cos x = -sin x
2. derivative of a1/2 = (1/2)*a-1/2 = 1/(4a)1/2
Multiplying the two we get the answer:
-sin(x)/(4cos x)1/2
The derivative with respect to 'x' of sin(pi x) ispi cos(pi x)
It is not totally clear to what the square root applies*; if just the 2, then: d/dx ((√2)sin x) = (√2) cos x if all of 2 sin x, then: d/dx (√(2 sin x)) = cos x / √(2 sin x) * for the second version I would expect "square root all of 2 sin x" but some people would write as given in the question meaning this, so I've given both just in case.
-cos(x) + constant
cos pi over four equals the square root of 2 over 2 This value can be found by looking at a unit circle. Cos indicates it is the x value of the point pi/4 which is (square root 2 over 2, square root 2 over 2)
That means you must take the derivative of the derivative. In this case, you must use the product rule. y = 6x sin x y'= 6[x (sin x)' + (x)' sin x] = 6[x cos x + sin x] y'' = 6[x (cos x)' + (x)' cos x + cos x] = 6[x (-sin x) + cos x + cos x] = 6[-x sin x + 2 cos x]
The derivative of cos x is -sin x, the derivative of square root of x is 1/(2 root(x)). Applying the chain rule, the derivative of cos root(x) is -sin x times 1/(2 root(x)), or - sin x / (2 root x).
The square root of x = x to the power of a half
Use the formula for the derivative of a power. The square root of (x-5) is the same as (x-5)1/2.
The derivative of cos(x) is negative sin(x). Also, the derivative of sin(x) is cos(x).
The derivative with respect to 'x' of sin(pi x) ispi cos(pi x)
The derivative of the natural log is 1/x, therefore the derivative is 1/cos(x). However, since the value of cos(x) is submitted within the natural log we must use the chain rule. Then, we multiply 1/cos(x) by the derivative of cos(x). We get the answer: -sin(x)/cos(x) which can be simplified into -tan(x).
3/(4*square root(x)) ....Mukesh
(cos x sin x) / (cos x sin x) = 1. The derivative of a constant, such as 1, is zero.
The derivative of cos(x) equals -sin(x); therefore, the anti-derivative of -sin(x) equals cos(x).
The derivative of sin (x) is cos (x). It does not work the other way around, though. The derivative of cos (x) is -sin (x).
The derivative, with respect to x, is -x/sqrt(1-x2)
Write sec x as a function of sines and cosines (in this case, sec x = 1 / cos x). Then use the division formula to take the first derivative. Take the derivative of the first derivative to get the second derivative. Reminder: the derivative of sin x is cos x; the derivative of cos x is - sin x.