Two friends are writing practice problems to study for a trigonometry test. Sam writes the following problem for his friend Anna to solve:

In right triangle ABC, the measure of angle C is 90 degrees, and the length of side c is 8 inches.
Solve the triangle.
Anna tells Sam that the triangle cannot be solved. Sam says that she is wrong.
Who is right? Explain your thinking

The side [tex]c[/tex] represents the hypotenuse of a right triangle as [tex]C = 90^{\circ}[/tex] and is opposite to that angle. There are two ways to solve this triangle trigonometrically:

i) Law of Sine

[tex]\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}[/tex] (1)

ii) Law of Cosine

[tex]c^{2} = a^{2} + b^{2} - 2\cdot a\cdot b \cdot \cos C[/tex] (2)

The Pythagorean Theorem is a particular case of the Law of Cosine for [tex]C = 90^{\circ}[/tex]

The triangle cannot be solved as there is an input missing, either another side or another angle. If [tex]C = 90^{\circ}[/tex], then (2) is reduced into this form:

[tex]c^{2} = a^{2}+b^{2}[/tex] (2b)

In this case we need to know the measure of either [tex]a[/tex] or [tex]b[/tex] to determine its counterpart and the values of the missing angles by (1). In nutshell, Anna is right.