00:01
Hello, in this question this problem is of rotation of axis first right.
00:08
So, we will draw this, this is en, this is point a right, this is et that is rotated at theta.
00:25
So, a has x, y coordinates.
00:29
So, it has this, this, this and this has this as well right.
00:47
So, this is the shift, let this be b, e, c, d right, a, b and this is o origin.
01:07
Now, since r a equals i, the old coordinates ab equals j, ac equals en, ad equals et.
01:24
So, in triangle afd right, angle daf equals theta, af equals et cos theta, also fd equals et sin theta which is equal to be as well right.
01:49
So, now according to this in triangle doe, oe equals od cos theta which is equal to ca cos theta.
02:04
So, therefore, od equals ca, why because oe is equal to this as well right parallelogram...