Application… | NUST Entrance Test Mathematics

In $\triangleABC$ if $\beta=90^{\circ}$, then according to law of cosine the value of the square of the side b is defined as:

Difficulty: Easy

A:

b^{2}=a^{2}+b^{2}-2ab

B:

b^{2}=b^{2}+b^{2}-2bc\cos\beta

C:

b^{2}=a^{2}+c^{2}

D:

b^{2}=a^{2}+c^{2}+2ac\cos\beta

In $\triangleABC$ if$\alpha=90^{\circ}$ then according to law of cosine the value of the square of the side a is defined as

Difficulty: Easy

A:

a^{2}=b^{2}+c^{2}

B:

a^{2}=a^{2}+c^{2}+2ac

C:

a^{2}=b^{2}+c^{2}+2bc\cos\alpha

D:

a^{2}=b^{2}+c^{2}-2bc\cos\alpha

If $\alpha, \beta\:and\:\gamma$ are the measures of the angles of a triangle, and a, b and c are the lengths of sides opposite these angles then according be law of cosine, the value of $cosine\gamma$ is defined as:

Difficulty: Easy

A:

\cos\gamma=\frac{a^{2}+c^{2}-b^{2}}{2ac}

B:

\cos\gamma=\frac{a^{2}+c^{2}-b^{2}}{2ac}

C:

\cos\gamma=\frac{a^{2}+c^{2}+2ab\cos\gamma}{b^{2}}

D:

\cos\gamma=\frac{b^{2}+c^{2}-a^{2}}{2bc}

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