What is the value of x in the measure of the angle?

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.