00:01
So we're given this vertex matrix matrix over here, and we're asked to reflect across y equals negative x.
00:07
And to reflect across y equals negative x, we have to multiply the vertex matrix on the left by this matrix over here.
00:17
What do i mean by on the left? take a look over here.
00:21
This is eventually how you will solve the problem, but we always multiply to the left of the vertex matrix, the matrix that's given to us that we have to reflect.
00:30
And so always put this matrix to the left and multiply.
00:36
And so we're going to do that.
00:38
We're going to multiply these two matrices.
00:40
And we know we can multiply them because this is a 2 by 2, and this is a 2 by 4.
00:54
And since the these two the column of one and the rule of another match we can multiply them so to get the first element over here what we're going to do is we're going to multiply this rule by this column so we're going to get zero times three is zero plus negative one times negative three is three that's what we got for the next element this element over here, what we're going to do is we're going to do the operation with this column over here.
01:35
So we're going to do 0 times 6 is 0 plus negative 1 times 3 is negative 3.
01:40
So we get negative 3 over here...