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
What is the name of the formula that Ramanujan discovered for approximating the value of the trigonometric function (\tan \theta)?
-
Ramanujan's Tangent Approximation Formula
-
Ramanujan's Trigonometric Approximation Formula
-
Ramanujan's Infinite Series Formula
-
Ramanujan's Modular Equation
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}).
Which of the following sequences is Cauchy?
-
$a_n = \frac{n}{n+1}$
-
$a_n = \frac{(-1)^n}{n}$
-
$a_n = \sin(n)$
-
$a_n = \cos(n)$
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 $|a_m - a_n| = |\frac{m}{m+1} - \frac{n}{n+1}| = \frac{|m(n+1) - n(m+1)|}{(m+1)(n+1)} = \frac{|m-n|}{(m+1)(n+1)} < \frac{1}{N(N+1)} < \varepsilon$.
What is the value of (\sin 45^\circ)?
-
\(\frac{1}{2}\)
-
\(\frac{1}{\sqrt{2}}\)
-
\(\frac{\sqrt{2}}{2}\)
-
\(\sqrt{2}\)
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}).
What is the general formula for the Madhava series?
-
$$sin(x) = x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
-
$$sin(x) = x - \frac{x^3}{3!} + \frac{x^5}{5!} + \frac{x^7}{7!} + \cdots$$
-
$$sin(x) = x + \frac{x^3}{3!} + \frac{x^5}{5!} + \frac{x^7}{7!} + \cdots$$
-
$$sin(x) = x + \frac{x^3}{3!} - \frac{x^5}{5!} - \frac{x^7}{7!} + \cdots$$
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.
What is the general formula for the Madhava series for the cosine function?
-
$$cos(x) = 1 - \frac{x^2}{2!} + \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
-
$$cos(x) = 1 + \frac{x^2}{2!} + \frac{x^4}{4!} + \frac{x^6}{6!} + \cdots$$
-
$$cos(x) = 1 - \frac{x^2}{2!} - \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
-
$$cos(x) = 1 + \frac{x^2}{2!} - \frac{x^4}{4!} - \frac{x^6}{6!} + \cdots$$
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.
The equation (\sin^2\theta + \cos^2\theta = 1) is known as:
-
Pythagorean theorem
-
Euler's formula
-
Trigonometric identity
-
Law of cosines
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.
The equation (\frac{d}{dx} \sin x = \cos x) is known as:
-
Chain rule
-
Product rule
-
Quotient rule
-
Power rule
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.
What is the solution to the equation sin(x) = 1/2?
-
x = π/6
-
x = π/3
-
x = π/4
-
x = π/2
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.
The formula $\sin^2 \theta + \cos^2 \theta = 1$ is known as the:
-
Pythagorean identity
-
Euler's formula
-
Trigonometric identity
-
Brahmagupta's formula
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.
The formula $\sin 2\theta = 2 \sin \theta \cos \theta$ is known as the:
-
Double-angle formula
-
Half-angle formula
-
Sum-to-product formula
-
Product-to-sum formula
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.
The formula $\cos \theta = \frac{1 - \tan^2 \theta}{1 + \tan^2 \theta}$ is known as the:
-
Pythagorean identity
-
Euler's formula
-
Trigonometric identity
-
Brahmagupta's formula
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.
The formula $\tan \theta = \frac{\sin \theta}{\cos \theta}$ is known as the:
-
Pythagorean identity
-
Euler's formula
-
Trigonometric identity
-
Brahmagupta's formula
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.
The formula $\sin (A + B) = \sin A \cos B + \cos A \sin B$ is known as the:
-
Pythagorean identity
-
Euler's formula
-
Sum-to-product formula
-
Product-to-sum formula
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.
The formula $\cos (A + B) = \cos A \cos B - \sin A \sin B$ is known as the:
-
Pythagorean identity
-
Euler's formula
-
Sum-to-product formula
-
Product-to-sum formula
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.
Which trigonometric function is used to calculate the longitude of a place?
-
Sine
-
Cosine
-
Tangent
-
Cosecant
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})).