Math Problem Statement

y=5sin^2 (x) find the equation of the tangent at x= pi/6

Solution

We are tasked with finding the equation of the tangent line to the curve y=5sin2(x)y = 5 \sin^2(x) at x=π6x = \frac{\pi}{6}. To do this, we need to:

  1. Differentiate yy with respect to xx to find the slope of the tangent line at x=π6x = \frac{\pi}{6}.
  2. Use the point-slope form of the tangent line equation to find the equation of the tangent.

Step 1: Differentiate y=5sin2(x)y = 5 \sin^2(x)

First, rewrite the equation using a chain rule-friendly form: y=5(sin(x))2y = 5 (\sin(x))^2 Now apply the chain rule to differentiate: dydx=52sin(x)cos(x)=10sin(x)cos(x)\frac{dy}{dx} = 5 \cdot 2 \sin(x) \cdot \cos(x) = 10 \sin(x) \cos(x) Using the double-angle identity sin(2x)=2sin(x)cos(x)\sin(2x) = 2 \sin(x) \cos(x), we simplify the derivative: dydx=5sin(2x)\frac{dy}{dx} = 5 \sin(2x)

Step 2: Find the slope at x=π6x = \frac{\pi}{6}

Substitute x=π6x = \frac{\pi}{6} into the derivative to find the slope of the tangent line: dydxx=π6=5sin(2π6)=5sin(π3)=532=532\frac{dy}{dx}\bigg|_{x = \frac{\pi}{6}} = 5 \sin\left(2 \cdot \frac{\pi}{6}\right) = 5 \sin\left(\frac{\pi}{3}\right) = 5 \cdot \frac{\sqrt{3}}{2} = \frac{5\sqrt{3}}{2} Thus, the slope of the tangent line is 532\frac{5\sqrt{3}}{2}.

Step 3: Find the point on the curve at x=π6x = \frac{\pi}{6}

We now find the yy-coordinate of the point where x=π6x = \frac{\pi}{6}: y=5sin2(π6)=5(12)2=514=54y = 5 \sin^2\left(\frac{\pi}{6}\right) = 5 \left(\frac{1}{2}\right)^2 = 5 \cdot \frac{1}{4} = \frac{5}{4} So the point on the curve is (π6,54)\left(\frac{\pi}{6}, \frac{5}{4}\right).

Step 4: Use the point-slope form to find the equation of the tangent

The point-slope form of a line is: yy1=m(xx1)y - y_1 = m(x - x_1) where mm is the slope, and (x1,y1)(x_1, y_1) is the point on the curve.

Substitute the slope 532\frac{5\sqrt{3}}{2} and the point (π6,54)\left(\frac{\pi}{6}, \frac{5}{4}\right) into the formula: y54=532(xπ6)y - \frac{5}{4} = \frac{5\sqrt{3}}{2}\left(x - \frac{\pi}{6}\right) This is the equation of the tangent line.

Would you like me to simplify this further or provide additional details?


Here are some related questions:

  1. How do we use the product rule for differentiating trigonometric functions?
  2. What is the geometric meaning of a tangent line to a curve?
  3. How would the tangent equation change if x=π3x = \frac{\pi}{3} instead?
  4. What is the significance of the double-angle identity in simplifying derivatives?
  5. How do we find the normal line to a curve at a given point?

Tip: When differentiating trigonometric functions, identities like the double-angle identity can often simplify your work.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Trigonometry
Tangent Line

Formulas

Derivative of y = 5sin^2(x): dy/dx = 5sin(2x)
Tangent line equation: y - y1 = m(x - x1)
Double-angle identity: sin(2x) = 2sin(x)cos(x)

Theorems

Chain rule
Point-slope form
Double-angle identity

Suitable Grade Level

Grades 10-12