# 13 Lecture

## Limits and Continuity of Trigonometric Functions

Trigonometric functions such as sine, cosine, and tangent are fundamental functions that appear in various areas of mathematics, science, and engineering.

## Important Mcq's Midterm & Finalterm Prepration Past papers included

What is the limit of the sine function as x approaches infinity?

a) 0

b) 1

c) does not exist

d) -1

What is the limit of the cosine function as x approaches ?/2?

a) 0

b) 1

c) does not exist

d) -1

What is the derivative of the function f(x) = cos(x) - 2sin(x)?

a) -cos(x) - 2cos(x)

b) -sin(x) - 2cos(x)

c) sin(x) - 2cos(x)

d) -sin(x) + 2cos(x)

Which of the following trigonometric functions has a vertical asymptote at x = ?/2?

a) sine

b) cosine

c) tangent

d) none of the above

What is the limit of the tangent function as x approaches ?/2 from the left?

a) -?

b) ?

c) does not exist

d) 0

Which of the following trigonometric functions is continuous on the entire real line?

a) sine

b) cosine

c) tangent

d) none of the above

Answer: d) none of the above

What is the derivative of the function f(x) = sin(x)cos(x)?

a) cos^2(x)

b) -cos^2(x)

c) 2sin(x)cos(x)

d) -2sin(x)cos(x)

Which of the following functions is not continuous at x = 0?

a) sin(x)/x

b) cos(x)/x

c) tan(x)/x

d) all of the above are continuous at x = 0

What is the limit of the function f(x) = sin(1/x) as x approaches 0?

a) 0

b) does not exist

c) 1

d) -1

What is the maximum value of the function f(x) = 2sin(x) + 3cos(x) on the interval [0, 2?]?

a) 5

b) -5

c) 2

d) 3

## Subjective Short Notes Midterm & Finalterm Prepration Past papers included

What is the definition of the sine function?

Answer: The sine function is defined as the y-coordinate of a point on the unit circle in the coordinate plane.

Is the limit of the sine function as x approaches zero defined? Why or why not?

Answer: No, the limit of the sine function as x approaches zero is not defined because the function oscillates between -1 and 1 as x approaches zero.

What is the limit of the cosine function as x approaches zero?

Answer: The limit of the cosine function as x approaches zero is 1.

What is the definition of continuity?

Answer: A function is said to be continuous at a point if the limit of the function at that point exists and is equal to the value of the function at that point.

Is the tangent function continuous at all points? Why or why not?

Answer: No, the tangent function is not continuous at certain points where it has vertical asymptotes.

What is the derivative of the sine function?

Answer: The derivative of the sine function is the cosine function.

What is the derivative of the cosine function?

Answer: The derivative of the cosine function is the negative sine function.

What is the derivative of the tangent function?

Answer: The derivative of the tangent function is the secant squared function.

How can the continuity of trigonometric functions be used to solve problems in calculus?

Answer: The continuity of trigonometric functions can be used to find critical points and solve optimization problems.

What is the maximum value of the function f(x) = sin(x) + cos(x) on the interval [0, 2?]?

Answer: The maximum value of the function f(x) = sin(x) + cos(x) on the interval [0, 2?] is 2, which occurs at x = ?/4 and 9?/4.

### Limits and Continuity of Trigonometric Functions

Calculus and analytical geometry deal with the study of limits and continuity of functions. One of the essential components of calculus is the study of trigonometric functions. In this article, we will explore the limits and continuity of trigonometric functions. Trigonometric functions such as sine, cosine, and tangent are fundamental functions that appear in various areas of mathematics, science, and engineering. These functions can be defined using a unit circle in the coordinate plane. The sine function is defined as the y-coordinate of a point on the unit circle, the cosine function is defined as the x-coordinate of a point on the unit circle, and the tangent function is defined as the ratio of the sine and cosine functions. The limits of trigonometric functions are important in calculus because they help us understand how these functions behave as the input approaches a particular value. For example, let us consider the limit of the sine function as x approaches zero. The sine function oscillates between -1 and 1 as x approaches zero. However, the limit of the sine function as x approaches zero does not exist because the function does not approach a particular value. Similarly, the limit of the cosine function as x approaches zero is 1 because the cosine function approaches 1 as x approaches zero. This property of the cosine function is known as continuity. A function is said to be continuous at a point if the limit of the function at that point exists and is equal to the value of the function at that point. The tangent function is not continuous at certain points because it has vertical asymptotes where the function is undefined. These vertical asymptotes occur when the cosine function approaches zero, and the tangent function approaches infinity or negative infinity. The tangent function is continuous at all other points. The limits of trigonometric functions are also important in calculating derivatives. The derivative of a function at a particular point is the slope of the tangent line to the graph of the function at that point. The derivative of the sine function is the cosine function, and the derivative of the cosine function is the negative sine function. The derivative of the tangent function is the secant squared function. The continuity of trigonometric functions can also be used to solve various problems in calculus. For example, suppose we want to find the maximum and minimum values of the function f(x) = sin(x) + cos(x) on the interval [0, 2?]. Since the sine and cosine functions are continuous on this interval, the function f(x) is also continuous on this interval. Therefore, we can find the critical points of f(x) by setting the derivative of f(x) equal to zero and solving for x. The critical points of f(x) are x = ?/4, 5?/4, and 9?/4. We can then evaluate f(x) at these critical points and the endpoints of the interval to find the maximum and minimum values of f(x) on the interval. The maximum value of f(x) is 2, which occurs at x = ?/4 and 9?/4, and the minimum value of f(x) is -2, which occurs at x = 5?/4. In conclusion, the study of limits and continuity of trigonometric functions is an important topic in calculus and analytical geometry. The limits and continuity of these functions help us understand how they behave as the input approaches a particular value and how they can be used to solve various problems in calculus.