The tangent of a circle can be defined as a straight line that touches the circle at one point.
In the given diagram:
The line EG touches the circle at one point, F. This line can be considered as a tangent of the circle.
A chord of a circle is any line segment that joins two points on the circumference of the said circle. The diameter is the longest chord of a circle, that passes through the center of the circle. In the given diagram, There are two lines that join two points on the circumference of the circle, those are lines DB and DF
An inscribed angle in a circle is formed by two chords that a common endpoint on the circumference (which forms the vertex of the angle)
On the given diagram there is only one inscribed angle formed by the line segments DB and DF, with vertex at point D.
The inscribed angle is m∠BDF