Q. Find all critical points of the function g(θ)=sin2(6θ).
Understand critical points: Understand what critical points are. Critical points of a function occur where the derivative is zero or undefined. To find the critical points of g(θ)=sin2(6θ), we need to find the derivative g′(θ) and solve for θ where g′(θ)=0 or where g′(θ) is undefined.
Find derivative of g(θ): Find the derivative of g(θ)=sin2(6θ). Using the chain rule, the derivative of sin2(u) with respect to u is 2sin(u)cos(u). Here, u=6θ, so we need to use the chain rule again to differentiate u with respect to θ, which gives us 6. Therefore, the derivative of g(θ) with respect to θ is g(θ)=sin2(6θ)1.
Simplify the derivative: Simplify the derivative.We can use the double-angle formula for sine, sin(2u)=2sin(u)cos(u), to simplify g′(θ). This gives us g′(θ)=6sin(2×6θ)=6sin(12θ).
Set derivative equal to zero: Set the derivative equal to zero to find critical points.To find the critical points, we need to solve 6sin(12θ)=0. Since the coefficient 6 is not zero, we can divide both sides by 6 to get sin(12θ)=0.
Solve sin(12θ)=0: Solve the equation sin(12θ)=0. The sine function is zero at integer multiples of π. Therefore, 12θ=nπ, where n is an integer. To find θ, we divide both sides by 12 to get θ=12nπ, where n is an integer.
Determine interval for theta: Determine the interval for theta. Since θ is an angle, we typically consider its values in a specific interval, such as [0,2π) for one full rotation. However, the problem does not specify an interval, so we will provide the general solution θ=n12π, where n is an integer.
Check for undefined points: Check for any points where the derivative is undefined. The derivative g′(θ)=6sin(12θ) is defined for all real numbers, so there are no critical points where the derivative is undefined.
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