SIN


Returns the sine of the given angle (in radians).

Syntax:

SIN(angle)

returns the (trigonometric) sine of angle, the angle in radians.To return the sine of an angle in degrees, use the RADIANS function.

Example:

SIN(PI()/2)

returns 1, the sine of PI/2 radians

SIN(RADIANS(30))

returns 0.5, the sine of 30 degrees


Application:

A Ferris Wheel


Let's imagine a Ferris wheel with the following characteristics:

  • Radius: 50 meters
  • Height of the center: 55 meters above the ground
  • Time for one full rotation: 20 minutes


We can model the height of a passenger pod on this Ferris wheel using a sine function. The general form of the sine function for this scenario is:

H(t)=Asin(B(t−C))+D


Where:

  • H(t) is the height of the pod in meters at time t in minutes.
  • A is the amplitude, which is the radius of the wheel, so A=50.
  • D is the vertical shift, which is the height of the center of the wheel, so D=55.
  • The period is 20 minutes. The value of B is calculated as B=2π/period=2π/20=π/10.
  • C is the horizontal shift. Let's assume we start our timer (t=0) when the pod is at its lowest point. The standard sine function starts at the midline, but a negative sine function starts at the lowest point. So we will use a negative sine function, which effectively shifts the standard sine function. The equation becomes: H(t)=−Asin(Bt)+D.


Putting it all together, the equation for the height of the pod is:

H(t)=−50sin(10π​t)+55


Let's use this function to calculate the height of the pod at various times during its rotation.

Time (minutes)

Calculation

Height (meters)

Description

A
B
C
D
1
0
H(0) = -50sin(0) + 55
55
The pod starts at the midline (at the same height as the center).
2
5
H(5) = −50sin(π/10*5)+55=−50sin(π/2)+55=−50(1)+55
5
The pod is at its lowest point (55 - 50).
3
10
H(10)=−50sin(π/10*10)+55=−50sin(π)+55=−50(0)+55
55
The pod is back at the midline.
4
15
H(15)=−50sin(π/10*15)+55=−50sin(3π/2)+55=−50(−1)+55
105
The pod is at its highest point (55 + 50).
5
20
H(20)=−50sin(π/10*20)+55=−50sin(2π)+55=−50(0)+55
55
The pod completes one full rotation and is back at the midline.




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