Math  /  Trigonometry

QuestionA right triangle has side lengths 3, 4, and 5 as shown below. Use these lengths to find cosB\cos{B}, tanB\tan{B}, and sinB\sin{B}.
cosB=\cos{B} = tanB=\tan{B} = sinB=\sin{B} =

Studdy Solution

STEP 1

What is this asking? We need to find the cosine, tangent, and sine of angle B in a right triangle with sides 3, 4, and 5. Watch out! Make sure to identify the correct sides relative to angle B: **adjacent**, **opposite**, and **hypotenuse**.

STEP 2

1. Identify the sides
2. Calculate cos B
3. Calculate tan B
4. Calculate sin B

STEP 3

Looking at angle B, we can see that the side **adjacent** to it is BC, which has a length of 33.
The side **opposite** to angle B is AC, with a length of 44.
Lastly, the **hypotenuse**, which is always opposite the right angle, is AB with a length of 55.

STEP 4

Remember **SOH CAH TOA**!
Cosine is **adjacent** over **hypotenuse**.
So, cosB=adjacenthypotenuse\cos{B} = \frac{\text{adjacent}}{\text{hypotenuse}}.

STEP 5

We've already identified the **adjacent** side as having a length of 33 and the **hypotenuse** as having a length of 55.
Therefore, cosB=35\cos{B} = \frac{3}{5}.

STEP 6

Again, using **SOH CAH TOA**, tangent is **opposite** over **adjacent**.
So, tanB=oppositeadjacent\tan{B} = \frac{\text{opposite}}{\text{adjacent}}.

STEP 7

We've identified the **opposite** side as having length 44 and the **adjacent** side as having length 33.
Thus, tanB=43\tan{B} = \frac{4}{3}.

STEP 8

One last time with **SOH CAH TOA**, sine is **opposite** over **hypotenuse**.
So, sinB=oppositehypotenuse\sin{B} = \frac{\text{opposite}}{\text{hypotenuse}}.

STEP 9

We've identified the **opposite** side as having length 44 and the **hypotenuse** as having length 55.
Therefore, sinB=45\sin{B} = \frac{4}{5}.

STEP 10

cosB=35\cos{B} = \frac{3}{5}, tanB=43\tan{B} = \frac{4}{3}, and sinB=45\sin{B} = \frac{4}{5}.

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