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Given tan(e)=−1, what is the value of sec(e)?
a) √2
b) −√2
c) −1
d) 1

User Mgroat
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1 Answer

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Final answer:

Given that tan(e)=-1, the value of sec(e) is found by using the reciprocal identity of cosine, which results in sec(e) being equal to -√2. This follows from the right triangle relationships and the Pythagorean theorem, where the angle associated with tan(e)=-1 leads to equal but opposite sides, resulting in a hypotenuse of √2 and a sec(e) value of -√2.

Step-by-step explanation:

The question asks us to find sec(e) given that tan(e)=-1. Remember that the secant function is the reciprocal of the cosine function, and in a right triangle where the tangent value is -1, this implies an angle where the opposite and adjacent sides are equal in magnitude but have opposite signs. According to the Pythagorean theorem, the hypotenuse will then be √2. Therefore, sec(e), being the reciprocal of cosine which is the adjacent over the hypotenuse, will have a value of √2 with a negative sign due to the adjacent side (cosine) being negative in the case of tan(e) = -1. The correct answer is b) ∑√2.

To find sec(e) using the given tan(e) value, start by writing the basic identity of secant in terms of cosine:

  • sec(e) = 1/cos(e)

Since tan(e) = -1, and tangent is the ratio of sine over cosine (sin(e)/cos(e)), it implies that sin(e) and cos(e) are equal in magnitude but opposite in sign and since we're dealing with a right-angled triangle, we can use the Pythagorean identity:

  • sin(e)2 + cos(e)2 = 1

With equal sides, this becomes 2cos(e)2 = 1, leading to cos(e) = √(1/2) = 1/√2, with the negative sign due to tan(e) being negative in the specific quadrant. Finally, sec(e) = 1/cos(e) gives us sec(e) = ∑√2.

User David Gilbertson
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