Geometry

Question Analysis  

The question asks which angle has the same cos θ as 45°, focusing on identifying angles in different quadrants with identical cosine values (same x-coordinate on the unit circle).  

 

Key Concept Explanation  

Cosine and Quadrants: Cos θ is positive in QI and QIV, negative in QII and QIII.  

Reference Angles: Angles in QIV that share a reference angle with QI have the same cosine value. For 45° (QI), the corresponding QIV angle is .  

 

Step-by-Step Solution  

1. Identify the reference angle for 45°:  

Reference angle = 45° (already in QI).  

2. Find the QIV angle with the same reference angle:  

QIV angle = .  

3. Verify cosine values:  

,  

.  

 

Option Analysis  

135°: Incorrect. Lies in QII,