1. The trigonometric expression, cos70° cos40° - sin70° sin40° is also equal to which of the following?
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Correct answer is option - 3
Explanation: Here we can use the formula cosAcosB – sinAsinB = cos(A + B).
This implies that cos70° cos40° - sin70° sin40° = cos(70° + 40°) ==> cos110°.
2. Which of the following represents the expression, 2sinA – sin2A?
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Correct answer is option - 1
Explanation: According to the formula, we have: sin2A = 2 sinAcosA.
Now we have, 2sinA – sin2A ==> 2sinA – 2 sinAcosA.
Factoring the common factor, we get: 2sinA (1 – cosA).
3. Which of the following is (cot x)/ (cosec x) equal to?
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Correct answer is option - 2
Explanation: Here, cot(x) can also be written as (cosx)/ (sinx) and cosec(x) can also be written as 1/sinx.
Now this implies, (cot x)/ (cosec x) = (cosx/ sinx)/ (1/sinx) ==> (cosx/ sinx ) * sinx = cosx.
4. In the third quadrant, which among the following trigonometric functions is positive?
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Correct answer is option - 3
Explanation: In the third quadrant, both tanθ and cotθ are positive.
Since tanθ is not given in the options, cotθ is the only right answer.
5. What is the radian measure of the angle 240°?
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Correct answer is option - 4
Explanation: 240° can be written in radian measure as 240° * (π/180°).
This can be simplified to 24π/18 which can be further simplified to 4π/3.