Math Problem Statement

Graph using mapping step by step describing each point and how you get the formula for the points: y=2sin(-3x-pie/2)+2

Solution

To graph the function y=2sin(3xπ2)+2y = 2\sin(-3x - \frac{\pi}{2}) + 2 step by step, we'll follow a structured process and analyze each transformation. Here's how you can proceed:


Step 1: Start with the basic sine function

The basic sine function is y=sin(x)y = \sin(x). Its graph oscillates between 1-1 and 11, has a period of 2π2\pi, and passes through the points:

  1. (0,0)(0, 0)
  2. (π2,1)(\frac{\pi}{2}, 1)
  3. (π,0)(\pi, 0)
  4. (3π2,1)(\frac{3\pi}{2}, -1)
  5. (2π,0)(2\pi, 0)

We will transform this graph step by step.


Step 2: Reflect the sine graph horizontally with 3x-3x

The negative sign in sin(3x)\sin(-3x) reflects the graph horizontally (around the y-axis). Points such as (π2,1)(\frac{\pi}{2}, 1) become (π2,1)(-\frac{\pi}{2}, 1), and (3π2,1)(\frac{3\pi}{2}, -1) becomes (3π2,1)(-\frac{3\pi}{2}, -1).

The coefficient 33 compresses the graph horizontally by a factor of 13\frac{1}{3}, reducing the period. The period of a sine function is given by 2πb\frac{2\pi}{|b|}, where bb is the coefficient of xx. For sin(3x)\sin(-3x), b=3b = -3, so the period becomes:

New Period=2π3.\text{New Period} = \frac{2\pi}{3}.

The key points now adjust as follows:

  1. Start at x=0x = 0 (still y=0y = 0).
  2. The first peak is at x=π6x = \frac{\pi}{6}.
  3. Cross zero at x=π3x = \frac{\pi}{3}.
  4. Reach the minimum at x=π2x = \frac{\pi}{2}.
  5. Complete one cycle at x=2π3x = \frac{2\pi}{3}.

Step 3: Phase shift π2-\frac{\pi}{2}

The π2-\frac{\pi}{2} term shifts the graph horizontally. Because it is subtracted, the graph shifts right by π2\frac{\pi}{2}.

New key points:

  1. Start at x=π2x = \frac{\pi}{2} (y-value remains 00).
  2. Peak at x=π2+π6=2π3x = \frac{\pi}{2} + \frac{\pi}{6} = \frac{2\pi}{3}.
  3. Zero at x=π2+π3=5π6x = \frac{\pi}{2} + \frac{\pi}{3} = \frac{5\pi}{6}.
  4. Minimum at x=π2+π2=πx = \frac{\pi}{2} + \frac{\pi}{2} = \pi.
  5. Complete the cycle at x=π2+2π3=4π3x = \frac{\pi}{2} + \frac{2\pi}{3} = \frac{4\pi}{3}.

Step 4: Vertical stretch and shift

The coefficient 22 outside the sine function stretches the graph vertically by a factor of 22. This means the amplitude increases to 22. The graph now oscillates between 2-2 and 22.

The final vertical shift of +2+2 moves the entire graph up by 2 units, so it oscillates between 00 and 44.

Final key points:

  1. Start at (π2,2)(\frac{\pi}{2}, 2) (middle line).
  2. Peak at (2π3,4)(\frac{2\pi}{3}, 4).
  3. Zero at (5π6,2)(\frac{5\pi}{6}, 2).
  4. Minimum at (π,0)(\pi, 0).
  5. Complete the cycle at (4π3,2)(\frac{4\pi}{3}, 2).

Formula Recap:

y=2sin(3xπ2)+2y = 2\sin(-3x - \frac{\pi}{2}) + 2

This formula describes:

  • A reflection and compression from sin(x)\sin(x).
  • A horizontal shift by π2\frac{\pi}{2} to the right.
  • A vertical stretch by 2.
  • A vertical shift by 2.

Final Tip for Plotting:

  1. Use the calculated key points to draw the curve smoothly.
  2. Label the axes and note the amplitude (00 to 44) and period (2π3\frac{2\pi}{3}).

Would you like a detailed sketch or further explanation?

Related Questions:

  1. How does a negative phase shift differ from a positive one in sine functions?
  2. How do you find the amplitude and period for any sine or cosine function?
  3. How do vertical shifts impact the graph of sinusoidal functions?
  4. What happens if the coefficient of xx inside sin(kx)\sin(kx) is fractional?
  5. How can this function be applied in real-world periodic phenomena?

Tip: Always start transformations from the basic graph sin(x)\sin(x), applying one modification at a time.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Trigonometry
Graph Transformations
Sine Function

Formulas

y = 2sin(-3x - π/2) + 2
Period of sine function: 2π / |b|
Amplitude of sine function: |a|

Theorems

Phase Shift Formula for Sine: x - c shifts the graph horizontally by c
Amplitude: Vertical stretch or compression of the graph
Period: Determines how often the sine function repeats

Suitable Grade Level

Grades 10-12