Find the Exact Value of the Expression $\cos 840 ^ { \circ }$

question 102

Multiple Choice

Find the exact value of the expression.
- $\cos 840 ^ { \circ }$

• A) \(- \frac { \sqrt { 3 } } { 2 }\)
• B) \(\frac { \sqrt { 2 } } { 2 }\)
• C) \(- \sqrt { 3 }\)
• D) \(- \frac { 1 } { 2 }\)

---

Definitions:

Double-Edged Effect

A situation or strategy that has both positive and negative outcomes or implications.

Overconfidence

A cognitive bias where a person's subjective confidence in their judgments is greater than the objective accuracy of those judgments.

Fundamental Attribution Error

The fundamental attribution error is the tendency to overemphasize personal characteristics and underestimate situational influences when explaining someone else's behavior.

Irrational Escalation

The phenomenon where individuals continue or intensify an action or investment beyond a rational point, often due to emotional commitment or previous investments.