Module 23 - Answers
 
Lesson 1
 
 Answer 1
 
23.1.1  

The values of t are restricted to nonnegative values and because x = t the values of x are also restricted to those values.

 
 Answer 2
 
23.1.2   Swapping x and y produces the inverse relation whose graph is the original graph reflected across the line y = x.

 
 Answer 3
 
23.1.3  

[0, 2 ] x [-4, 4] x [-2, 2]

The first interval given in the window coordinates above represents t-values, the second and third intervals represent x and y-values, respectively.

 
 Answer 4
 
23.1.4  

x = 7sin t - sin 7t

y = 7cos t - cos 7t

x = 8sin t - sin 8t

y = 8cos t - cos 8t

The number of petals is N - 1 in the epicycloid

x = N sin t - sin N t

y = N cos t - cos N t

 
Lesson 2
 
 Answer 1
 
23.2.1 dydx(0.5) = 2.08583, which agrees with the value found using the "Derivative" feature of the Graph screen.
 
 Answer 2
 
23.2.2   The slope of the tangent line when t = 2 is dydx(2) 0.642093
 
 Answer 3
 
23.2.3  

The window shown is [- , ] x [-3, 3] x [-5, 5].

The equation of the tangent to the curve when t = 2 is y 0.642093x + 0.715815.

 
Lesson 3
 
 Answer 1
 
23.3.1 The arc length is 3/2 units.
 
Self Test
 
 Answer 1
 
 
 Answer 2
 
1/2
 
 Answer 3
 
7/4
 
 Answer 4
 
y = 0.5x – 0.25
 
 Answer 5
 
3.34122 units
 
 

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