Calculus Examples
y=(sin(x))cos(x)y=(sin(x))cos(x)
Step 1
Let y=f(x)y=f(x), take the natural logarithm of both sides ln(y)=ln(f(x))ln(y)=ln(f(x)).
ln(y)=ln((sin(x))cos(x))ln(y)=ln((sin(x))cos(x))
Step 2
Expand ln((sin(x))cos(x))ln((sin(x))cos(x)) by moving cos(x)cos(x) outside the logarithm.
ln(y)=cos(x)ln(sin(x))ln(y)=cos(x)ln(sin(x))
Step 3
Step 3.1
Differentiate the left hand side ln(y)ln(y) using the chain rule.
y′y=cos(x)ln(sin(x))
Step 3.2
Differentiate the right hand side.
Step 3.2.1
Differentiate cos(x)ln(sin(x)).
y′y=ddx[cos(x)ln(sin(x))]
Step 3.2.2
Differentiate using the Product Rule which states that ddx[f(x)g(x)] is f(x)ddx[g(x)]+g(x)ddx[f(x)] where f(x)=cos(x) and g(x)=ln(sin(x)).
y′y=cos(x)ddx[ln(sin(x))]+ln(sin(x))ddx[cos(x)]
Step 3.2.3
Differentiate using the chain rule, which states that ddx[f(g(x))] is f′(g(x))g′(x) where f(x)=ln(x) and g(x)=sin(x).
Step 3.2.3.1
To apply the Chain Rule, set u as sin(x).
y′y=cos(x)(ddu[ln(u)]ddx[sin(x)])+ln(sin(x))ddx[cos(x)]
Step 3.2.3.2
The derivative of ln(u) with respect to u is 1u.
y′y=cos(x)(1uddx[sin(x)])+ln(sin(x))ddx[cos(x)]
Step 3.2.3.3
Replace all occurrences of u with sin(x).
y′y=cos(x)(1sin(x)ddx[sin(x)])+ln(sin(x))ddx[cos(x)]
y′y=cos(x)(1sin(x)ddx[sin(x)])+ln(sin(x))ddx[cos(x)]
Step 3.2.4
Convert from 1sin(x) to csc(x).
y′y=cos(x)(csc(x)ddx[sin(x)])+ln(sin(x))ddx[cos(x)]
Step 3.2.5
The derivative of sin(x) with respect to x is cos(x).
y′y=cos(x)csc(x)cos(x)+ln(sin(x))ddx[cos(x)]
Step 3.2.6
Raise cos(x) to the power of 1.
y′y=cos1(x)cos(x)csc(x)+ln(sin(x))ddx[cos(x)]
Step 3.2.7
Raise cos(x) to the power of 1.
y′y=cos1(x)cos1(x)csc(x)+ln(sin(x))ddx[cos(x)]
Step 3.2.8
Use the power rule aman=am+n to combine exponents.
y′y=cos(x)1+1csc(x)+ln(sin(x))ddx[cos(x)]
Step 3.2.9
Add 1 and 1.
y′y=cos2(x)csc(x)+ln(sin(x))ddx[cos(x)]
Step 3.2.10
The derivative of cos(x) with respect to x is -sin(x).
y′y=cos2(x)csc(x)+ln(sin(x))(-sin(x))
Step 3.2.11
Simplify.
Step 3.2.11.1
Reorder terms.
y′y=cos2(x)csc(x)-sin(x)ln(sin(x))
Step 3.2.11.2
Simplify each term.
Step 3.2.11.2.1
Rewrite csc(x) in terms of sines and cosines.
y′y=cos2(x)1sin(x)-sin(x)ln(sin(x))
Step 3.2.11.2.2
Combine cos2(x) and 1sin(x).
y′y=cos2(x)sin(x)-sin(x)ln(sin(x))
y′y=cos2(x)sin(x)-sin(x)ln(sin(x))
Step 3.2.11.3
Simplify each term.
Step 3.2.11.3.1
Factor cos(x) out of cos2(x).
y′y=cos(x)cos(x)sin(x)-sin(x)ln(sin(x))
Step 3.2.11.3.2
Separate fractions.
y′y=cos(x)1⋅cos(x)sin(x)-sin(x)ln(sin(x))
Step 3.2.11.3.3
Convert from cos(x)sin(x) to cot(x).
y′y=cos(x)1cot(x)-sin(x)ln(sin(x))
Step 3.2.11.3.4
Divide cos(x) by 1.
y′y=cos(x)cot(x)-sin(x)ln(sin(x))
y′y=cos(x)cot(x)-sin(x)ln(sin(x))
y′y=cos(x)cot(x)-sin(x)ln(sin(x))
y′y=cos(x)cot(x)-sin(x)ln(sin(x))
y′y=cos(x)cot(x)-sin(x)ln(sin(x))
Step 4
Isolate y′ and substitute the original function for y in the right hand side.
y′=(cos(x)cot(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5
Step 5.1
Simplify each term.
Step 5.1.1
Rewrite cot(x) in terms of sines and cosines.
y′=(cos(x)cos(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.1.2
Multiply cos(x)cos(x)sin(x).
Step 5.1.2.1
Combine cos(x) and cos(x)sin(x).
y′=(cos(x)cos(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.1.2.2
Raise cos(x) to the power of 1.
y′=(cos1(x)cos(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.1.2.3
Raise cos(x) to the power of 1.
y′=(cos1(x)cos1(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.1.2.4
Use the power rule aman=am+n to combine exponents.
y′=(cos(x)1+1sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.1.2.5
Add 1 and 1.
y′=(cos2(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
y′=(cos2(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
y′=(cos2(x)sin(x)-sin(x)ln(sin(x)))(sin(x))cos(x)
Step 5.2
Apply the distributive property.
y′=cos2(x)sin(x)sin(x)cos(x)-sin(x)ln(sin(x))sin(x)cos(x)
Step 5.3
Combine cos2(x)sin(x) and sin(x)cos(x).
y′=cos2(x)sin(x)cos(x)sin(x)-sin(x)ln(sin(x))sin(x)cos(x)
Step 5.4
Multiply sin(x) by sin(x)cos(x) by adding the exponents.
Step 5.4.1
Move sin(x)cos(x).
y′=cos2(x)sin(x)cos(x)sin(x)-(sin(x)cos(x)sin(x))ln(sin(x))
Step 5.4.2
Multiply sin(x)cos(x) by sin(x).
Step 5.4.2.1
Raise sin(x) to the power of 1.
y′=cos2(x)sin(x)cos(x)sin(x)-(sin(x)cos(x)sin1(x))ln(sin(x))
Step 5.4.2.2
Use the power rule aman=am+n to combine exponents.
y′=cos2(x)sin(x)cos(x)sin(x)-sin(x)cos(x)+1ln(sin(x))
y′=cos2(x)sin(x)cos(x)sin(x)-sin(x)cos(x)+1ln(sin(x))
y′=cos2(x)sin(x)cos(x)sin(x)-sin(x)cos(x)+1ln(sin(x))
Step 5.5
Cancel the common factor of sin(x)cos(x) and sin(x).
Step 5.5.1
Factor sin(x) out of cos2(x)sin(x)cos(x).
y′=sin(x)(cos2(x)sin(x)cos(x)-1)sin(x)-sin(x)cos(x)+1ln(sin(x))
Step 5.5.2
Cancel the common factors.
Step 5.5.2.1
Multiply by 1.
y′=sin(x)(cos2(x)sin(x)cos(x)-1)sin(x)⋅1-sin(x)cos(x)+1ln(sin(x))
Step 5.5.2.2
Cancel the common factor.
y′=sin(x)(cos2(x)sin(x)cos(x)-1)sin(x)⋅1-sin(x)cos(x)+1ln(sin(x))
Step 5.5.2.3
Rewrite the expression.
y′=cos2(x)sin(x)cos(x)-11-sin(x)cos(x)+1ln(sin(x))
Step 5.5.2.4
Divide cos2(x)sin(x)cos(x)-1 by 1.
y′=cos2(x)sin(x)cos(x)-1-sin(x)cos(x)+1ln(sin(x))
y′=cos2(x)sin(x)cos(x)-1-sin(x)cos(x)+1ln(sin(x))
y′=cos2(x)sin(x)cos(x)-1-sin(x)cos(x)+1ln(sin(x))
Step 5.6
Reorder factors in cos2(x)sin(x)cos(x)-1-sin(x)cos(x)+1ln(sin(x)).
y′=sin(x)cos(x)-1cos2(x)-sin(x)cos(x)+1ln(sin(x))
y′=sin(x)cos(x)-1cos2(x)-sin(x)cos(x)+1ln(sin(x))