Mathematics

Trigonometric Identities and Equations

223 Questions

Solve a variety of questions based on trigonometric identities and mathematical equations. Key areas covered include double angle formulas, the law of sines, and quadrant angles. This material helps students preparing for advanced mathematics exams, UPSC, and state public service commissions.

Double angle formulasLaw of sinesTrigonometric quadrantsLaplace transformSecant functionTaylor series

Trigonometric Identities and Equations Questions

Multiple choice

What is the name of the formula that Ramanujan discovered for approximating the value of the trigonometric function (\tan \theta)?

  1. Ramanujan's Tangent Approximation Formula

  2. Ramanujan's Trigonometric Approximation Formula

  3. Ramanujan's Infinite Series Formula

  4. Ramanujan's Modular Equation

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ramanujan's Tangent Approximation Formula is a series that provides an approximation of the value of the trigonometric function (\tan \theta). It is given by the formula (\tan \theta = \frac{\theta}{1 + \frac{\theta^2}{3} + \frac{2\theta^4}{15} + \frac{17\theta^6}{315} + \cdots}).

Multiple choice

Which of the following sequences is Cauchy?

  1. $a_n = \frac{n}{n+1}$
  2. $a_n = \frac{(-1)^n}{n}$
  3. $a_n = \sin(n)$
  4. $a_n = \cos(n)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The sequence $a_n = \frac{n}{n+1}$ is Cauchy because for any $\varepsilon > 0$, we can choose $N = \frac{1}{\varepsilon} + 1$. Then, for all $m, n > N$, we have $|a_m - a_n| = |\frac{m}{m+1} - \frac{n}{n+1}| = \frac{|m(n+1) - n(m+1)|}{(m+1)(n+1)} = \frac{|m-n|}{(m+1)(n+1)} < \frac{1}{N(N+1)} < \varepsilon$.

Multiple choice

What is the value of (\sin 45^\circ)?

  1. \(\frac{1}{2}\)
  2. \(\frac{1}{\sqrt{2}}\)
  3. \(\frac{\sqrt{2}}{2}\)
  4. \(\sqrt{2}\)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The value of (\sin 45^\circ) can be found using the unit circle or by using the trigonometric ratio (\sin \theta = \frac{opposite}{hypotenuse}). In a 45-45-90 triangle, the opposite side and the hypotenuse are both equal to (\sqrt{2}). Therefore, (\sin 45^\circ = \frac{\sqrt{2}}{\sqrt{2}} = \frac{\sqrt{2}}{2}).

Multiple choice

What is the general formula for the Madhava series?

  1. $$sin(x) = x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
  2. $$sin(x) = x - \frac{x^3}{3!} + \frac{x^5}{5!} + \frac{x^7}{7!} + \cdots$$
  3. $$sin(x) = x + \frac{x^3}{3!} + \frac{x^5}{5!} + \frac{x^7}{7!} + \cdots$$
  4. $$sin(x) = x + \frac{x^3}{3!} - \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general formula for the Madhava series is $$sin(x) = x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$. This series converges for all values of x.

Multiple choice

What is the general formula for the Madhava series for the cosine function?

  1. $$cos(x) = 1 - \frac{x^2}{2!} + \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
  2. $$cos(x) = 1 + \frac{x^2}{2!} + \frac{x^4}{4!} + \frac{x^6}{6!} + \cdots$$
  3. $$cos(x) = 1 - \frac{x^2}{2!} - \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
  4. $$cos(x) = 1 + \frac{x^2}{2!} - \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The general formula for the Madhava series for the cosine function is $$cos(x) = 1 - \frac{x^2}{2!} + \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$. This series converges for all values of x.

Multiple choice

The equation (\sin^2\theta + \cos^2\theta = 1) is known as:

  1. Pythagorean theorem

  2. Euler's formula

  3. Trigonometric identity

  4. Law of cosines

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The equation (\sin^2\theta + \cos^2\theta = 1) is known as a trigonometric identity, which is an equation that is true for all values of the variable.

Multiple choice

The equation (\frac{d}{dx} \sin x = \cos x) is known as:

  1. Chain rule

  2. Product rule

  3. Quotient rule

  4. Power rule

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The equation (\frac{d}{dx} \sin x = \cos x) is known as the chain rule, which is used to find the derivative of a composite function.

Multiple choice

What is the solution to the equation sin(x) = 1/2?

  1. x = π/6

  2. x = π/3

  3. x = π/4

  4. x = π/2

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To solve the equation sin(x) = 1/2, we can use the inverse sine function (also known as arcsin). The inverse sine of 1/2 is π/6. Therefore, the solution to the equation sin(x) = 1/2 is x = π/6.

Multiple choice

The formula $\sin^2 \theta + \cos^2 \theta = 1$ is known as the:

  1. Pythagorean identity

  2. Euler's formula

  3. Trigonometric identity

  4. Brahmagupta's formula

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formula $\sin^2 \theta + \cos^2 \theta = 1$ is a fundamental trigonometric identity that expresses the relationship between the sine and cosine functions of an angle.

Multiple choice

The formula $\sin 2\theta = 2 \sin \theta \cos \theta$ is known as the:

  1. Double-angle formula

  2. Half-angle formula

  3. Sum-to-product formula

  4. Product-to-sum formula

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The formula $\sin 2\theta = 2 \sin \theta \cos \theta$ is a double-angle formula in trigonometry, which expresses the sine of twice an angle in terms of the sine and cosine of the original angle.

Multiple choice

The formula $\cos \theta = \frac{1 - \tan^2 \theta}{1 + \tan^2 \theta}$ is known as the:

  1. Pythagorean identity

  2. Euler's formula

  3. Trigonometric identity

  4. Brahmagupta's formula

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formula $\cos \theta = \frac{1 - \tan^2 \theta}{1 + \tan^2 \theta}$ is a trigonometric identity that expresses the relationship between the cosine and tangent functions of an angle.

Multiple choice

The formula $\tan \theta = \frac{\sin \theta}{\cos \theta}$ is known as the:

  1. Pythagorean identity

  2. Euler's formula

  3. Trigonometric identity

  4. Brahmagupta's formula

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formula $\tan \theta = \frac{\sin \theta}{\cos \theta}$ is a fundamental trigonometric identity that expresses the relationship between the tangent, sine, and cosine functions of an angle.

Multiple choice

The formula $\sin (A + B) = \sin A \cos B + \cos A \sin B$ is known as the:

  1. Pythagorean identity

  2. Euler's formula

  3. Sum-to-product formula

  4. Product-to-sum formula

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formula $\sin (A + B) = \sin A \cos B + \cos A \sin B$ is a sum-to-product formula in trigonometry, which expresses the sine of the sum of two angles in terms of the sines and cosines of the individual angles.

Multiple choice

The formula $\cos (A + B) = \cos A \cos B - \sin A \sin B$ is known as the:

  1. Pythagorean identity

  2. Euler's formula

  3. Sum-to-product formula

  4. Product-to-sum formula

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formula $\cos (A + B) = \cos A \cos B - \sin A \sin B$ is a sum-to-product formula in trigonometry, which expresses the cosine of the sum of two angles in terms of the cosines and sines of the individual angles.

Multiple choice

Which trigonometric function is used to calculate the longitude of a place?

  1. Sine

  2. Cosine

  3. Tangent

  4. Cosecant

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The tangent function is used to calculate the longitude of a place, using the formula (\lambda = \tan^{-1}(\frac{\sin t}{\cos t \sin \phi_0 - \tan \delta \cos \phi_0})).