Which country did the scholar Euclid belong to?

If △ABC,  ∠BAC = 120⁰ and  AD⊥BC then what is the complementary angle of ∠ABD = ?

In which century B.C. Euclid put down the definition of geometric measurement process and different procedures in his book 'Elements' ?

The measure of an acute angle is –

What is the name of the book written by Euclid on the theme of geometry

Practical Geometry

Measure of right angle –

A triangle in which the measure of each angle is less than ____ is an acute-angled triangle.

If △ABC,  ∠BAC = 120⁰ and  AD⊥BC then, ∠ADC = ?

A line -
(i) Has no definite length
(ii) Has no end points
(iii) Has no definite breadth
Which one is correct ?