25 points
verify that parallelogram abcd with vertices a(-5,-1) , b(-9,6), c(-1,5) and d(3,-2) is a rhombus by showing that it is a parallelogram with perpendicular diagonals.

if you could show all the steps you used

If the slope of AB = CD and BC = AD it's a parallelogram:

Slope of AB = 6+1 / -9+5 = -7/4

CD = -2-5 / 3+1 = -74

These are equal.

BC = 5-6 / -1 +9 = -1/8

AD = -2 +1 / 3+5 = -1/8

These are also equal so it is a parallelogram.

Now to find if the diagonals are perpendicular find the slope of the perpensicular points:

AC = 5 +1 / -1 +5 = 6/4 = 3/2

BD = 6+2 / -9 -3 = 8/-12 = -2/3

Because BD is the reciprocal of AC, this means they are perpendicular.

And because AB is not perpendicular to AD ( AB and AD are not reciprocals) it is a rhombus.

answer:

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

explanation:

service only with 20% tip  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

in the opening of the question the word 'service' is associated only with the pretax value.

the closing part of the question asks: how much did she pay for the  

service

−−−−−−  

so technically the answer is  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

however, the intention of the question provider may have been that your answer is to be  

$

87.12

(

1

+

8

100

)

=

$

94.09

to 2 decimal places.

'

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

tony b

mar 21, 2017

answer:

trying to explain it another way

explanation:

service charge  

.

→

$

72.60

20% tip  

20

100

×

$

72.60

=

$

14.52

−−−−−−  

←

add

$

87.12

tax  

8

100

×

$

87.12

=

$

6.97

−−−−−  

←

add

$

94.09

related questions

x = 2

step-by-step explanation:

if sr parallel to ba then the sides bc and ac are in proportion, that is

= ← substitute values

= ( cross- multiply )

27x = 6(4x + 1)

27x = 24x + 6 ( subtract 24x from both sides )

3x = 6 ( divide both sides by 3 )

x = 2