Geometry

Question Analysis  

Determine the Quadrant I angle where , using 30-60-90 triangle ratios.  

 

Key Concept Explanation  

Cosine in 30-60-90 Triangles:  

. For , the adjacent side is (in a triangle), so .  

 

Step-by-Step Solution  

1. Recall special angle cosine values:  

,  

.  

2. Match to given value:  

corresponds to .  

 

Option Analysis  

0°: Incorrect ()  

30°: Incorrect (

Click "Show Answer" to reveal the answer and analysis