BackStep-by-Step Guidance for Differential Calculus Midterm Exam Questions
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Q1. If and , where and are in the interval , evaluate .
Background
Topic: Trigonometric Identities and Angle Addition Formulas
This question tests your ability to use trigonometric identities, specifically the sine addition formula, and to determine the values of trigonometric functions given information about angles in specific quadrants.
Key Terms and Formulas
Recall the signs of trigonometric functions in different quadrants.
Step-by-Step Guidance
Start by drawing reference triangles for and in the correct quadrants (since ).
For , use to find and . Remember that is negative in quadrants II and IV, but since , $A$ is in quadrant III or IV.
For , use to find and . is negative in quadrants II and III, but so $B$ is in quadrant III.
Express , , , and in terms of their reference triangles, making sure to use the correct signs based on the quadrant.
Substitute these values into the formula and simplify as much as possible.
Try solving on your own before revealing the answer!
Final Answer:
After finding all the necessary sine and cosine values and substituting into the addition formula, you get .
Q2. Find all values of in the interval that satisfy the equation: .
Background
Topic: Solving Trigonometric Equations
This question tests your ability to manipulate and solve trigonometric equations within a given interval.
Key Terms and Formulas
Standard values and zeros of , , and on
Step-by-Step Guidance
Rewrite as to simplify the equation.
Group like terms and factor the equation if possible.
Set each factor equal to zero and solve for in .
Check for extraneous solutions, especially where or may be undefined.
Try solving on your own before revealing the answer!
Final Answer:
These are the solutions in that satisfy the equation.
Q3. Find a formula for the inverse of .
Background
Topic: Inverse Functions
This question tests your ability to find the inverse of a rational function by solving for in terms of and then interchanging variables.
Key Terms and Formulas
Inverse function: If , then
To find the inverse, solve for in terms of , then swap $x$ and $y$
Step-by-Step Guidance
Let .
Multiply both sides by to clear the denominator.
Expand and collect all terms involving on one side and constants on the other.
Solve for in terms of .
Swap and to write .
Try solving on your own before revealing the answer!
Final Answer:
This is the formula for the inverse function.
Q4. Prove the identity:
Background
Topic: Trigonometric Identities
This question tests your ability to manipulate and prove trigonometric identities using algebraic and trigonometric properties.
Key Terms and Formulas
Pythagorean identities:
Step-by-Step Guidance
Start with the left side: .
Multiply numerator and denominator by to rationalize the denominator.
Simplify the denominator using the Pythagorean identity.
Express the result in terms of .
Try solving on your own before revealing the answer!
Final Answer: Identity is proven as
Both sides are equivalent after simplification.
Q5. Solve for :
Background
Topic: Exponential Equations
This question tests your ability to solve equations involving exponential functions by substitution and factoring.
Key Terms and Formulas
Let to reduce the equation to a quadratic in .
Quadratic formula:
Properties of logarithms and exponentials.
Step-by-Step Guidance
Let , so the equation becomes .
Factor or use the quadratic formula to solve for .
Set equal to each solution for and solve for using logarithms.
Check for extraneous solutions (e.g., must be positive).
Try solving on your own before revealing the answer!
Final Answer: or
These are the real solutions for .
Q6. Find the limit if it exists (Do not use L'Hospital's Rule):
Background
Topic: Limits and Continuity
This question tests your understanding of evaluating limits using algebraic manipulation, factoring, rationalization, and the Squeeze Theorem.
Key Terms and Formulas
Limit laws
Squeeze Theorem
Algebraic simplification techniques
Step-by-Step Guidance
Identify the form of the limit (e.g., , , etc.).
Try to factor, rationalize, or otherwise simplify the expression.
If the limit is indeterminate, consider using the Squeeze Theorem or other limit properties.
Substitute the value if possible after simplification.
Try solving on your own before revealing the answer!
Final Answer: Answers depend on each subpart (a)-(e); see your work for details.
Each limit is evaluated using algebraic or squeeze theorem techniques as appropriate.
Q7. Find the horizontal asymptote(s) of the curve .
Background
Topic: Asymptotes of Rational and Exponential Functions
This question tests your ability to find horizontal asymptotes by analyzing the end behavior of the function as and .
Key Terms and Formulas
Horizontal asymptote: and
Dominant terms for large
Step-by-Step Guidance
Analyze the behavior as : Which terms dominate in numerator and denominator?
Analyze the behavior as .
Compute the limits to determine the horizontal asymptotes.
Try solving on your own before revealing the answer!
Final Answer: and
These are the horizontal asymptotes as and respectively.
Q8. Use the Intermediate Value Theorem to show that the equation has at least one real root.
Background
Topic: Intermediate Value Theorem (IVT)
This question tests your understanding of the IVT and how to apply it to show the existence of a root for a continuous function.
Key Terms and Formulas
IVT: If is continuous on and and have opposite signs, then there exists such that .
Step-by-Step Guidance
Define .
Choose two values and in (or another interval) and compute and .
Show that and have opposite signs.
State that is continuous on .
Conclude by the IVT that there is at least one root in .
Try solving on your own before revealing the answer!
Final Answer: There is at least one real root by the IVT.
Because and have opposite signs and is continuous, a root exists in the interval.
Q9. Use the definition of derivative to find the derivative of (No marks will be given for computing the derivative by any other method).
Background
Topic: Definition of the Derivative
This question tests your ability to use the limit definition of the derivative to compute for a given function.
Key Terms and Formulas
Definition:
Step-by-Step Guidance
Write and .
Compute and simplify the numerator.
Divide by and simplify further.
Take the limit as to find .
Try solving on your own before revealing the answer!
Final Answer:
This is the derivative using the limit definition.
Q10. Find (You do not need to simplify your answer):
Background
Topic: Product Rule, Chain Rule, and Derivatives of Logarithmic, Exponential, and Trigonometric Functions
This question tests your ability to differentiate composite and product functions using the appropriate rules.
Key Terms and Formulas
Product Rule:
Chain Rule:
Derivatives of , , , ,
Step-by-Step Guidance
For each part, identify which rules (product, chain, etc.) are needed.
Apply the product rule where appropriate.
Apply the chain rule for composite functions.
Write out the derivative expressions, but do not simplify.
Try solving on your own before revealing the answer!
Final Answer: See your derivative expressions for each part (a)-(c).
Each derivative is written out using the appropriate rules, as required.