Questions: Use the Unit Circle to find the exact value of the trig function. cos(45°)
a. 1/2
b. -√3/2
c. √2/2
d. 1
Transcript text: Use the Unit Circle to find the exact value of the trig function. $\cos \left(45^{\circ}\right)$
a. $\frac{1}{2}$
b. $-\frac{\sqrt{3}}{2}$
c. $\frac{\sqrt{2}}{2}$
d. 1
Solution
Solution Steps
Step 1: Identify the angle on the Unit Circle
The angle given is \(45^{\circ}\). On the unit circle, \(45^{\circ}\) corresponds to the point \(\left(\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2}\right)\).
Step 2: Recall the definition of cosine on the Unit Circle
The cosine of an angle in the unit circle is equal to the x-coordinate of the corresponding point.
Step 3: Determine the cosine value
For \(45^{\circ}\), the x-coordinate is \(\frac{\sqrt{2}}{2}\). Therefore, \(\cos(45^{\circ}) = \frac{\sqrt{2}}{2}\).
Step 4: Match the value with the given options
The value \(\frac{\sqrt{2}}{2}\) corresponds to option c.
Step 1: Identify the angle on the Unit Circle
The angle given is \(45^{\circ}\). On the unit circle, \(45^{\circ}\) corresponds to the point \(\left(\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2}\right)\).
Step 2: Recall the definition of cosine on the Unit Circle
The cosine of an angle in the unit circle is equal to the x-coordinate of the corresponding point.
Step 3: Determine the cosine value
For \(45^{\circ}\), the x-coordinate is \(\frac{\sqrt{2}}{2}\). Therefore, \(\cos(45^{\circ}) = \frac{\sqrt{2}}{2}\).
Step 4: Match the value with the given options
The value \(\frac{\sqrt{2}}{2}\) corresponds to option c.