Find the Exact Value of the Expression Using the Provided $\cos ( \mathrm { s } - \mathrm { t } )$

question 417

Multiple Choice

Find the exact value of the expression using the provided information.
-Find $\cos ( \mathrm { s } - \mathrm { t } )$ given that $\cos s = \frac { \sqrt { 5 } } { 5 }$ , with $\mathrm { s }$ in quadrant $\mathrm { I }$ , and $\sin \mathrm { t } = - \frac { \sqrt { 3 } } { 2 }$ , with $\mathrm { t }$ in quadrant IV.

• A) \(\frac { \sqrt { 5 } + 2 \sqrt { 15 } } { 10 }\)
• B) \(\frac { \sqrt { 5 } - \sqrt { 15 } } { 9 }\)
• C) \(- \frac { \sqrt { 5 } } { 10 }\)
• D) \(\frac { \sqrt { 5 } - 2 \sqrt { 15 } } { 10 }\)

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Definitions:

Unstated Premise

An implicit assumption in an argument that is not directly expressed but is necessary for the argument's conclusion.

O Proposition

A type of categorical proposition that denotes some S are not P, where S stands for the subject and P for the predicate.

Enthymeme

A syllogism in which one of the premises is implicit or assumed rather than explicitly stated.

Hedge Fund

A pooled investment fund that employs different strategies to earn active return, or alpha, for their investors.