Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

The graph of a sinusoidal function intersects its midline at 
(0,-7) and then has a minimum point at 
((pi)/(4),-9).
Write the formula of the function, where 
x is entered in radians.

The graph of a sinusoidal function intersects its midline at (0,7) (0,-7) and then has a minimum point at (π4,9) \left(\frac{\pi}{4},-9\right) .\newlineWrite the formula of the function, where x x is entered in radians.

Full solution

Q. The graph of a sinusoidal function intersects its midline at (0,7) (0,-7) and then has a minimum point at (π4,9) \left(\frac{\pi}{4},-9\right) .\newlineWrite the formula of the function, where x x is entered in radians.
  1. Determine Amplitude: Determine the amplitude of the function.\newlineSince the midline is at y=7y = -7 and the minimum point is at y=9y = -9, the amplitude is the distance from the midline to the minimum, which is 22 units.\newlineAmplitude (AA) = midlineminimum=7(9)=2|\text{midline} - \text{minimum}| = |-7 - (-9)| = 2
  2. Identify Midline: Identify the midline DD of the function.\newlineThe midline is given as y=7y = -7.\newlineD=7D = -7
  3. Determine Period: Determine the period TT of the function.\newlineSince the function reaches its minimum at π4\frac{\pi}{4} and the next similar point (maximum or minimum) would be after a full period, we can infer that the period is 44 times the xx-coordinate of the minimum point.\newlineT=4×(π4)=πT = 4 \times \left(\frac{\pi}{4}\right) = \pi
  4. Calculate Value of B: Calculate the value of B using the period.\newlineThe period TT is related to BB by the formula T=2πBT = \frac{2\pi}{B}.\newlineπ=2πB\pi = \frac{2\pi}{B}\newlineB=2B = 2
  5. Determine Phase Shift: Determine the phase shift CC. Since the function intersects its midline at (0,7)(0, -7), there is no horizontal shift, so the phase shift CC is 00. C=0C = 0
  6. Choose Sinusoidal Function: Choose the correct sinusoidal function.\newlineBecause the function has a minimum point at (π/4,9)(\pi/4, -9), we should use a cosine function that starts at a maximum. However, since we have a minimum point, we need to reflect the cosine function over the midline. This means we will use a negative cosine function.\newlinef(x)=Acos(Bx+C)+Df(x) = -A\cos(Bx + C) + D
  7. Write Final Equation: Write the final equation of the sinusoidal function.\newlineSubstitute the values of AA, BB, CC, and DD into the equation.\newlinef(x)=2cos(2x)7f(x) = -2\cos(2x) - 7

More problems from Write equations of sine and cosine functions using properties