+0

# need help with geometry pls

0
200
2
+569

pls need help can you explain?

Feb 20, 2018

#1
+99592
+2

5)

We can look at the diagram.....but....there is a way to solve this with some math

New Point  =  ( Old Point - Dilation Center)*(Scale Factor) + Dilation Center

Note that:    (a, b) - (c,d)  = ( a - c, b - d)

And  C(a, b)  = (Ca , Cb)     where C is a constant

SF  = Scale Factor

So   using the new point  (-8, - 3)  and  the old point (4, - 3)  we have

(-8, - 3)  =  [ (4, -3) - (-4, - 3)] * SF  +  ( -4, -3)

Subtract  (-4, - 3)  from both sides

(-8, -3) - ( -4, -3)  =  [ (4, -3) - (-4, - 3)] * SF

(-8, -3) - ( -4, -3)  = [ (8, 0) ] * SF

(-4, 0)  =  (8, 0) * SF

To find the scale factor, take the ratio  of the x coordinate on the left side and divide it by  the x coordinate on the right side

-4 / 8  =   - 1/2   =  scale factor

Feb 20, 2018
#2
+99592
+2

6)

Going through a similar process

(5, -3)  =  [  ( -5, - 3)  - (-3, -3) ] *SF  +  (-3, -3)

(5, - 3) - (-3, -3)  =  [ ( -2, 0)] *SF

(8,0)   =   (-2, 0 ) * SF

8 / - 2   =   - 4   =  SF

Feb 20, 2018