BackPrecalculus Exam 2 Review – Step-by-Step Study Guidance
Study Guide - Smart Notes
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Q1. A twenty-five foot ladder just reaches the top of a house and forms an angle of 41.5° with the wall of the house. How tall is the house? Round to the nearest 0.1 foot.
Background
Topic: Right Triangle Trigonometry
This question tests your ability to use trigonometric ratios (specifically sine, cosine, or tangent) to find the height of a right triangle given an angle and the length of the hypotenuse.
Key Terms and Formulas
Hypotenuse: The side opposite the right angle (the ladder in this case).
Opposite side: The side opposite the given angle (the height of the house).
Sine function:
Step-by-Step Guidance
Draw a right triangle representing the situation, labeling the ladder as the hypotenuse (25 ft), the angle with the wall as , and the height of the house as the side opposite the angle.
Set up the sine equation: , where is the height of the house.
Rearrange the equation to solve for : .
Try solving on your own before revealing the answer!
Final Answer: 16.5 ft
ft$
We used the sine function to find the height of the house, given the angle and the hypotenuse.
Q2. To find the length of the span of a proposed ski lift from A to B, a surveyor measures the angle DAB to be 25°, then walks off a distance of L = 1950 feet to C and measures the angle ACB to be 15°. What is the distance from A to B?
Background
Topic: Law of Sines (Oblique Triangles)
This question tests your ability to use the Law of Sines to find an unknown side in a triangle when given two angles and one side.
Key Terms and Formulas
Law of Sines:
Given: , ft,
Step-by-Step Guidance
Draw triangle ABC, labeling the given angles and side. Let (the distance you want to find).
Find the third angle in the triangle: .
Set up the Law of Sines: .
Rearrange to solve for : .
Try solving on your own before revealing the answer!
Final Answer: 2906.43 ft
Using the Law of Sines and plugging in the values, you find the length of the ski lift span.
Q3. The polar coordinates of a point are given: . Find the rectangular coordinates of the point.
Background
Topic: Polar to Rectangular Coordinate Conversion
This question tests your ability to convert from polar coordinates to rectangular coordinates .
Key Terms and Formulas
Step-by-Step Guidance
Identify and .
Calculate .
Calculate .
Recall that and .
Try solving on your own before revealing the answer!
Final Answer:
We used the conversion formulas and the exact values for sine and cosine at radians.
Q4. The letters x and y represent rectangular coordinates. Write the equation using polar coordinates .
Background
Topic: Rectangular to Polar Equation Conversion
This question tests your ability to rewrite equations from rectangular form to polar form using the relationships between and .
Key Terms and Formulas
Step-by-Step Guidance
Substitute and into the equation: .
Expand and simplify: .
Factor out: .
Divide both sides by to solve for .
Try solving on your own before revealing the answer!
Final Answer:
We substituted the polar forms for and and solved for .
Q5. The letters r and θ represent polar coordinates. Write the equation using rectangular coordinates .
Background
Topic: Polar to Rectangular Equation Conversion
This question tests your ability to convert a polar equation to rectangular form using the relationships between and .
Key Terms and Formulas
Step-by-Step Guidance
Multiply both sides by : .
Expand: .
Recall that and .
Substitute for and for to write the equation in terms of $x$ and .
Try solving on your own before revealing the answer!
Final Answer:
We used the relationships between polar and rectangular coordinates to rewrite the equation.
Q6. The rectangular coordinates of a point are given: (5, -5). Find polar coordinates for this point. Let and .
Background
Topic: Rectangular to Polar Coordinate Conversion
This question tests your ability to convert from rectangular coordinates to polar coordinates .
Key Terms and Formulas
(adjust for quadrant)
Step-by-Step Guidance
Calculate .
Calculate .
Since the point is in the fourth quadrant, adjust to the correct value in .
Try solving on your own before revealing the answer!
Final Answer:
We calculated using the distance formula and found using the arctangent, adjusting for the correct quadrant.