Question

Line HF is tangent to circle D at point E. SEgment DE is the radius of circle D, what is true about DEF?

A.angle DEF is congruent to angle DEH
B.angle DEF is an acute angle
C.angle DEF is an obtuse angle
D.angle DEF is a straight angle

Answer 1

D.angle def is an obtuse angle

Answer 2

When we draw a circle with the centre at D and have a tangent HF to the circle D at point E, the angle DEF will be a right angle.

In other words angle DEF = 90 degrees

Since HF, the tangent, is a straight line, the other angle DEH should also be = 90 degrees because the straight line has an angle of 180 degrees

Therefore angle DEF = angle DEH = 90 degrees

Therefore, angle DEF is congruent to angle DEH (Option A)