Question

is a perpendicular drawn from a vertex to its opposite side of the triangle.
It is also called the of the triangle.

Answer 1

Altitude is a perpendicular drawn from a vertex to its opposite side of the triangle.
It is also called the height of the triangle.

For example,
AD is the altitude of the triangle $△ABC,$ drawn from the vertex A on the opposite side BC.
AD is perpendicular to BC.