Use the Half-Angle Formulas to Find the Exact Value of the Trigonometric

question 199

Multiple Choice

Use the Half-angle Formulas to find the exact value of the trigonometric function.
- $\cos 22.5 ^ { \circ }$

• A) \(\frac { 1 } { 2 } \sqrt { 2 - \sqrt { 2 } }\)
• B) \(- \frac { 1 } { 2 } \sqrt { 2 - \sqrt { 2 } }\)
• C) \(- \frac { 1 } { 2 } \sqrt { 2 + \sqrt { 2 } }\)
• D) \(\frac { 1 } { 2 } \sqrt { 2 + \sqrt { 2 } }\)

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Definitions:

Intercostal Group

Muscles located between the ribs that assist with the breathing process by aiding in the expansion and contraction of the chest cavity.

Spinotrapezius

A back muscle that assists in moving the scapula for the lifting of the arm.

Masseter

A facial muscle that plays a major role in the chewing of food by raising the lower jaw towards the upper jaw.

Elevate Mandible

Elevating the mandible refers to the action of lifting or closing the lower jaw, a movement primarily facilitated by the masseter and temporalis muscles.