If ∆ABC is right angled at C, CD ⊥ AB, ∠A = 55° then, ∠ACD =?

Correct option is A

Given:

Triangle ∆ABC is right-angled at C.

CD ⊥ AB (perpendicular from C to hypotenuse AB).

∠A = 55°. 

Concept Used: 

For a right angle triangle; 

Sum of angle is 180^o 

Solution:

In ∆ACD (formed by perpendicular CD):

∠ACD + ∠A + ∠ADC = 180° (as it is a right triangle).

∠ACD + 55° + 90° = 180°

∠ACD = 180° - 90° - 55°

∠ACD = 35°.