Answer:
4 horses and 8 ducks.
Step-by-step explanation:
Let the number of ducks be d and the number of horses be h.
d + h = 12
Now ducks have 2 feet and horses have 4 so:
2d + 4h = 32
Multiply the first equation by 2
2d + 2h = 24
Subtract this equation from the second equation:
4h - 2h = 32 - 24
2h = 8
h = 4.
So there were 4 horses and 12 - 4 = 8 ducks.
Answer:


Step-by-step explanation:
First we define two generic vectors in our
space:


By definition we know that Euclidean norm on an 2-dimensional Euclidean space
is:

Also we know that the inner product in
space is defined as:

So as first condition we have that both two vectors have Euclidian Norm 1, that is:

and

As second condition we have that:


Which is the same:

Replacing the second condition on the first condition we have:

Since
we have two posible solutions,
or
. If we choose
, we can choose next the other solution for
.
Remembering,

The two vectors we are looking for are:

The answer is c ................