Questions:
Complete the table. The area when is 10o has been given to help you verify your expressions for columns b and c. Show all
calculations.
MATH 113 PRECALCULUS II Dr. Kowski
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Angle Smaller base
of trapezoid
a
Larger base
of trapezoid
b
Height of
trapezoid
c
Area
c
a b
2
10o 8 feet 22.1 sq. ft.
20o 8 feet
30o 8 feet
40o 8 feet
50o 8 feet
60o 8 feet
70o 8 feet
80o 8 feet
90o 8 feet
b. Write a general equation for the area as a function of .
MATH 113 PRECALCULUS II Dr. Kowski
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c. Use your graphing calculator to view a graph of the area function from part b. Also, view the table on your calculator. Hand-sketch the graph of the area function [0, 180] x [0, 90]. Be sure to label axes increments or points AND label the axes according to the problem content.
Provide exact coordinates for any intercepts.
MATH 113 PRECALCULUS II Dr. Kowski 4
d. TRACE on your graphing calculator, what angle provides the maximum area?
e. Using TABLE on your calculator, what is the maximum area and what angle provides this maximum area?
f. Do you get different answers for parts d and e above? Explain why or why not.
Answers:
Part a
Angle | Smaller base of trapezoid a | Larger base of trapezoid b | Height of Trapezoid c | Area: c*((a+b)/2) |
10 | 8 | 23.75692405 | 1.389185421 | 22.1 |
20 | 8 | 23.03508193 | 1.389185421 | 21.6 |
30 | 8 | 21.85640646 | 1.389185421 | 20.7 |
40 | 8 | 20.25671109 | 1.389185421 | 19.6 |
50 | 8 | 18.28460175 | 1.389185421 | 18.3 |
60 | 8 | 16 | 1.389185421 | 16.7 |
70 | 8 | 13.47232229 | 1.389185421 | 14.9 |
80 | 8 | 10.77837084 | 1.389185421 | 13.0 |
90 | 8 | 8 | 1.389185421 | 11.1 |
Part b
Part c
Part d
X-axis value with the biggest y-axis value)
Part e
X-axis value with the biggest y-axis value)
Part f
Answers are different. The graph provides more values than the table.