In the given figure, ABCD is a square. Angle DEC = 75 degrees. What is the value (in degrees) of angle EFA?

Correct option is C

Given:

ABCD is a square.

DB and FC intersect at E.

∠DEC = 75°

Find ∠EFA.

Concept Used:

Diagonal of a square makes 45° with its sides.

Angles formed by intersecting lines.

Linear pair angles.

Solution:

Since DB is the diagonal of the square, it makes an angle of 45° with side AB.

Given:
∠DEC = 75° 

So, ∠FEB = 75° ( vertically opposite)

∠FBE = 45° ( made by diagonal) 

Now, 

∠EFA =  ∠FBE + ∠FEB  ( for triangle EFA) 

∠EFA =  75 + 45 = 120°