Math  /  Trigonometry

QuestionVerify the identity using the fundamental trigonometric identities. tan(θ)+cot(θ)=sec(θ)csc(θ)\tan (\theta)+\cot (\theta)=\sec (\theta) \csc (\theta)
Use Reciprocal Identities to rewrite the expression in terms of sine and cosin tan(θ)+cot(θ)=sin(θ)cos(θ)+sin(θ)=cos(θ)sin(θ)\begin{aligned} \tan (\theta)+\cot (\theta) & =\frac{\sin (\theta)}{\cos (\theta)}+\frac{\square}{\sin (\theta)} \\ & =\frac{\square}{\cos (\theta) \sin (\theta)} \end{aligned}
Use a Pythagorean Identity to simplify the numerator of the expression. =cos(θ)sin(θ)=\frac{\square}{\cos (\theta) \sin (\theta)}
Use Reciprocal Identities again to simplify. ==\square Submit Answer
15. [1/1 Points] DETAILS MY NOTES SPRECALC8 7.1.042.

Studdy Solution

STEP 1

What is this asking? We need to prove that tan(θ)+cot(θ)\tan(\theta) + \cot(\theta) is exactly the same as sec(θ)csc(θ)\sec(\theta)\csc(\theta) using some cool trig tricks! Watch out! Don't mix up your reciprocal and Pythagorean identities!
Also, be super careful with your signs when simplifying.

STEP 2

1. Rewrite in terms of Sine and Cosine
2. Common Denominator
3. Pythagorean Identity
4. Reciprocal Identities

STEP 3

We know that tan(θ)\tan(\theta) is the same as sin(θ)cos(θ)\frac{\sin(\theta)}{\cos(\theta)} and cot(θ)\cot(\theta) is the same as cos(θ)sin(θ)\frac{\cos(\theta)}{\sin(\theta)}.
So, let's **rewrite** our starting equation: tan(θ)+cot(θ)=sin(θ)cos(θ)+cos(θ)sin(θ) \tan(\theta) + \cot(\theta) = \frac{\sin(\theta)}{\cos(\theta)} + \frac{\cos(\theta)}{\sin(\theta)} This makes things easier to work with!

STEP 4

To add these two fractions, we need a **common denominator**.
Let's multiply the first fraction by sin(θ)sin(θ)\frac{\sin(\theta)}{\sin(\theta)} (which is just a fancy way of multiplying by **one**) and the second fraction by cos(θ)cos(θ)\frac{\cos(\theta)}{\cos(\theta)} (also a fancy **one**!). sin(θ)cos(θ)sin(θ)sin(θ)+cos(θ)sin(θ)cos(θ)cos(θ) \frac{\sin(\theta)}{\cos(\theta)} \cdot \frac{\sin(\theta)}{\sin(\theta)} + \frac{\cos(\theta)}{\sin(\theta)} \cdot \frac{\cos(\theta)}{\cos(\theta)}

STEP 5

This gives us: sin2(θ)cos(θ)sin(θ)+cos2(θ)cos(θ)sin(θ) \frac{\sin^2(\theta)}{\cos(\theta)\sin(\theta)} + \frac{\cos^2(\theta)}{\cos(\theta)\sin(\theta)} Now we can **add** the fractions: sin2(θ)+cos2(θ)cos(θ)sin(θ) \frac{\sin^2(\theta) + \cos^2(\theta)}{\cos(\theta)\sin(\theta)}

STEP 6

Remember the **Pythagorean identity**: sin2(θ)+cos2(θ)=1\sin^2(\theta) + \cos^2(\theta) = 1?
Let's **use** it!
We can **replace** the numerator with a nice and simple **1**: 1cos(θ)sin(θ) \frac{1}{\cos(\theta)\sin(\theta)}

STEP 7

We know that 1cos(θ)\frac{1}{\cos(\theta)} is sec(θ)\sec(\theta) and 1sin(θ)\frac{1}{\sin(\theta)} is csc(θ)\csc(\theta).
So, we can **rewrite** our expression as: 1cos(θ)1sin(θ)=sec(θ)csc(θ) \frac{1}{\cos(\theta)} \cdot \frac{1}{\sin(\theta)} = \sec(\theta)\csc(\theta)

STEP 8

We've shown that tan(θ)+cot(θ)=sec(θ)csc(θ)\tan(\theta) + \cot(\theta) = \sec(\theta)\csc(\theta)!
We've successfully **verified** the identity!

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