Mathematics
Trigonometric Identities
87 Questions
Trigonometric identities focus on solving equations using tangent, sine, and cosine properties. Questions involve half angle formulas and slope calculations. This topic is a staple in the quantitative aptitude section of major competitive examinations.
Tangent propertiesAngle formulasTrigonometric equationsHalf angle identitiesSlope calculations
Trigonometric Identities Questions
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1/cosx
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1/secx
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sinx/cosx
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cosx/sinx
C
Correct answer
Explanation
The tangent function is defined as tan x = sin x / cos x, which is the ratio of sine to cosine for the same angle. Options A and B are incorrect reciprocals, while D would be cotangent (cot x = cos x / sin x).
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1+tanx
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1/tanx
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1/cosx
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1/sinx
C
Correct answer
Explanation
The secant function is defined as sec x = 1/cos x, the reciprocal of cosine. Option D (1/sin x) would be cosecant (csc x), and options A and B are incorrect expressions. This is a fundamental reciprocal identity in trigonometry.
B
Correct answer
Explanation
tan(45°) = sin(45°)/cos(45°) = (√2/2)/(√2/2) = 1. At 45 degrees, sine and cosine have equal values, so their ratio is 1. Infinity would mean cos(45°) = 0, which is false.
C
Correct answer
Explanation
The expression simplifies using trigonometric identities: (1-cos x)/(1+cos x) = tan^2(x/2). Thus, y = tan^-1(tan(x/2)) = x/2. The first derivative dy/dx is 1/2, and the second derivative d^2y/dx^2 is 0. The stored answer correctly identifies the second derivative.
B
Correct answer
Explanation
To solve for p, first evaluate tan(45°) = 1. Then the equation becomes 3(1) + p = 8, which simplifies to 3 + p = 8. Subtracting 3 from both sides gives p = 5. This is a basic trigonometry substitution problem combined with linear equation solving.
C
Correct answer
Explanation
The derivative of cos(x) is -sin(x). This follows from the rules of trigonometric differentiation. Conversely, the derivative of sin(x) is positive cos(x). Distractors like -cos(x) or -tan(x) do not follow the standard differentiation rules for this function.
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sec2 x
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csc2 x
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-csc2 x
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-sec2 x
A
Correct answer
Explanation
The derivative of tan x is sec^2 x. This follows from writing tan x = sin x/cos x and applying the quotient rule. The notation 'sec2 x' in option A is meant to represent sec²(x). Options B and C use csc (cosecant), which is unrelated to tan derivatives. Option D has the wrong sign.
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tan(90)
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cosec(0)
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sec(90)
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cot(90)
D
Correct answer
Explanation
Cot(90°) equals 0, which is a defined value. The other three trigonometric expressions are undefined because they involve division by zero: tan(90°) = sin(90°)/cos(90°) = 1/0, cosec(0°) = 1/sin(0°) = 1/0, and sec(90°) = 1/cos(90°) = 1/0.
D
Correct answer
Explanation
tan 45 = 1, sin 90 = 1, and cos 0 = 1. Adding them together: 1 + 1 + 1 = 3.
B
Correct answer
Explanation
sin 45 = 0.707 and tan 45 = 1. The inequality 0.707 > 1 is false, so the correct answer is False.
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0
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1
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sin 90
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cos 0
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tan 45
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infinity
B,C,D,E
Correct answer
Explanation
tan 30 = 1/sqrt(3) and tan 60 = sqrt(3). Their product is 1. sin 90, cos 0, and tan 45 are all equal to 1. Therefore, all marked options are mathematically correct.
A,B,C,D
Correct answer
Explanation
Evaluating: tan 60 = 1.732, cos 45 = 0.707, sin 45 = 0.707, tan 30 = 0.577. Sum = 3.723, which is greater than 0, 1, 2, and 3 but less than 4. Therefore options A, B, C, and D are all correct.
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1/2
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1/root(2)
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1/3
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1/root(3)
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root(3)/2
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none of above
C
Correct answer
Explanation
If tan(2x) = 4sqrt(2)/7, use tan(2x) = 2tan(x)/(1-tan²x) to find tan(x) = sqrt(2)/4. Then sin(x) = tan(x)/sqrt(1+tan²x). Calculation: sin(x) = (sqrt(2)/4) / sqrt(1 + 2/16) = (sqrt(2)/4) / (3/sqrt(8)) = (sqrt(2)/4) * (2sqrt(2)/3) = 4/12 = 1/3.
A
Correct answer
Explanation
The identity tan θ = 1/(cot θ) is true because cot θ is defined as 1/tan θ. Therefore, tan θ = 1/(cot θ) is mathematically correct for all values where both functions are defined. This reciprocal relationship is fundamental in trigonometry.
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tan(x/y)
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sin(x/y)
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atan2(x,y)
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cos(x/y)
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pow(x,y)
C
Correct answer
Explanation
This mathematical function is used to return arc tangent of the given expression x/y.