Asksia AI LOGO

Sia

Question
Math
Posted 6 months ago

The angle θ1\theta_{1} is located in Quadrant I\mathrm{I}, and sin(θ1)=1161\sin \left(\theta_{1}\right)=\frac{11}{61}.
What is the value of cos(θ1)\cos \left(\theta_{1}\right) ?
Express your answer exactly.
cos(θ1)=
\cos \left(\theta_{1}\right)=

\square
Sign in to unlock the answer
Answer from Sia
Posted 6 months ago
Solution by Steps
step 1
Given that sin(θ1)=1161\sin(\theta_1) = \frac{11}{61} and θ1\theta_1 is in Quadrant I
step 2
Use the Pythagorean identity: sin2(θ)+cos2(θ)=1\sin^2(\theta) + \cos^2(\theta) = 1
step 3
Substitute sin(θ1)\sin(\theta_1) into the identity: (1161)2+cos2(θ1)=1\left(\frac{11}{61}\right)^2 + \cos^2(\theta_1) = 1
step 4
Calculate sin2(θ1)\sin^2(\theta_1): (1161)2=1213721\left(\frac{11}{61}\right)^2 = \frac{121}{3721}
step 5
Solve for cos2(θ1)\cos^2(\theta_1): cos2(θ1)=11213721\cos^2(\theta_1) = 1 - \frac{121}{3721}
step 6
Simplify the expression: cos2(θ1)=372137211213721=36003721\cos^2(\theta_1) = \frac{3721}{3721} - \frac{121}{3721} = \frac{3600}{3721}
step 7
Take the square root of cos2(θ1)\cos^2(\theta_1) to find cos(θ1)\cos(\theta_1): cos(θ1)=36003721\cos(\theta_1) = \sqrt{\frac{3600}{3721}}
step 8
Since θ1\theta_1 is in Quadrant I, cos(θ1)\cos(\theta_1) is positive: cos(θ1)=6061\cos(\theta_1) = \frac{60}{61}
[1] Answer
cos(θ1)=6061\cos(\theta_1) = \frac{60}{61}
Key Concept
Pythagorean Identity in Trigonometry
Explanation
The Pythagorean identity sin2(θ)+cos2(θ)=1\sin^2(\theta) + \cos^2(\theta) = 1 is used to find the cosine of an angle when the sine is known, especially when the angle is in the first quadrant where both sine and cosine are positive.

Not the question you are looking for? Ask here!

Enter question by text

Enter question by image

Upgrade to Asksia Pro

Join a AskSia's Pro Plan, and get 24/7 AI tutoring for your reviews, assignments, quizzes and exam preps.

Unlimited chat query usages
Strong algorithms that better know you
Early access to new release features
Study Other Question