Math  /  Trigonometry

Question1. Jennifer says that sinA=614,cosA=814\sin A=\frac{6}{14}, \cos A=\frac{8}{14}, and tanA=68\tan A=\frac{6}{8}. Do you agree or disagree? If you agree, explain why. If you disagree, explain what she did incorrectly and provide the correct solution.

Studdy Solution

STEP 1

What is this asking? Is Jennifer right about the sine, cosine, and tangent of angle A, given some side lengths? Watch out! Remember SOH CAH TOA!
Don't mix up which sides go with which trig function.
Also, make sure your triangle is a right triangle before using these relationships!

STEP 2

1. Check for Right Triangle
2. Calculate Sine
3. Calculate Cosine
4. Calculate Tangent

STEP 3

Let's see if this is a right triangle using the Pythagorean Theorem.
If a2+b2=c2a^2 + b^2 = c^2, where cc is the **longest side**, then we've got a right triangle!
We have sides with lengths 66, 88, and 1414.
Is 62+826^2 + 8^2 equal to 14214^2?
Let's find out!

STEP 4

62+82=36+64=1006^2 + 8^2 = 36 + 64 = 100 142=19614^2 = 196 Since 100100 does not equal 196196, this is *not* a right triangle.

STEP 5

Jennifer says sinA=614\sin A = \frac{6}{14}.
Since sine is defined as the **opposite side** over the **hypotenuse**, and 66 *could* be the opposite side and 1414 *could* be the hypotenuse (if it were a right triangle), this *might* seem right at first glance.
But, since it's *not* a right triangle, we can't use SOH CAH TOA!

STEP 6

Jennifer's cosA=814\cos A = \frac{8}{14} has the same issue.
Cosine is the **adjacent side** over the **hypotenuse**, so 88 and 1414 are in the right spots, but we can't use cosine here because it's not a right triangle!

STEP 7

Finally, Jennifer's tanA=68\tan A = \frac{6}{8} looks like **opposite** over **adjacent**, which is correct for tangent.
But again, we can't use tangent because it's not a right triangle!

STEP 8

Jennifer is incorrect!
We can't use SOH CAH TOA because the triangle isn't a right triangle.
Since 62+821426^2 + 8^2 \ne 14^2, the Pythagorean Theorem isn't satisfied.

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