Answer:
Triangle
Explanation:
A triangle is a closed figure bounded by straight lines.
A triangle has three sides, three angles and three vertices.
Normally any triangle is uniquely determined by any 3 independent measures,
It may be either 2 angles one side, or two sides, one included angle, or any other detail.
By having 3 known dimensions of a triangle, to find out other unknown is known as solving a triangle.
Hence right answer is
Solving a _triangle____ is the process of calculating unknown side lengths or angle measures of a triangle if certain of the side lengths and/or angle measures are known.