If a is the distance between (0,0) and (5,7)
if (x1,y1)=(5,7)
applying in the formula; we get
a= \sqrt{( x_{1}-x_{2})^{2}+(y_{1}-y_{2})^{2}  }
a=8.6 unit
1 5 1
This is a question from the chapter Co-ordinate Geometry.
For this, I can't give a detailed explanation, but there is a formula for finding answers to such question.
Distance =  \sqrt{ (x_{1}- x_{2}) + ( y_{1} -  y_{2}  ) } .......................(1)
Here, x1, y1 and x2, y2 are the respective co-ordinates of the given points.
So we need to find the distance between origin and 5,7
We know that origin is 0,0
So we actually need to find the distance b/w 0,0 and 5,7
Lets take x1 as 0, x2 as 5, y1 as 0 and y2 as 7.
So, using the formula (1) and solving by putting x1 as 0, x2 as 5, y1 as 0 and y2 as 7, we get distance as 8.6023 units.
All the best !            :-)