Question

The height of a triangular window is (x + 7) cm and the base measures (3x) cm. If the area of the
window is 66 cm2, what is the height of the window?

Answer 1

A. 12 cm
B. 11 cm
C. 51 cm
D. 4 cm

Answer 2

can you help me?

Answer 3

What you can do is to use the formula for the area of a triangle. \[A = \frac{ bh }{ 2 }\]

Answer 4

ok so is it D?

Answer 5

@Isaiah.Feynman

Answer 6

nope not D

use the formula given

area = (1/2)(x + 7)(3x)

know where to go from here?

Answer 7

I didn't solve it.

Answer 8

so it would it be 12 ?

Answer 9

please stop guessing

Answer 10

do you know how to multiply out

area = (1/2)(x + 7)(3x)?

it's ok to say no

Answer 11

yes

Answer 12

ok, let me know what you get

Answer 13

0.5x+3.5+2.5?

Answer 14

uh not quite

Answer 15

3x(x+7) = ?

Answer 16

hint: (use distribution)

Answer 17

3x+21

Answer 18

not quite

what is 3x*x?

Answer 19

3x^2

Answer 20

good!

now what is 3x*7?

Answer 21

21x

Answer 22

good!

now put it all together

what is 3x(x+7)?

Answer 23

3x^2+21x

Answer 24

good!

now we have

(1/2)(3x^2 + 21x) = 66

multiplying both sides by 2 gives us

3x^2 + 21x = 132

know where to go from here?

Answer 25

dont we divide?

Answer 26

what would you like to divide?

Answer 27

would we divide 132 and 66

Answer 28

nope, remember that 66 isn't part of our equation anymore

our equation is now

3x^2 + 21x = 132

Answer 29

we CAN divide both sides by 3. what do we get then?

Answer 30

so we would divide 132 by 3?

Answer 31

yes, but also divide the left side too

Answer 32

what is 3x^2 + 21x divided by 3?

Answer 33

44

Answer 34

nope not quite

Answer 35

what is 3x^2 divided by 3?

Answer 36

3

Answer 37

nope...

Answer 38

hint:

3A divided by 3 is A
3x^2 divided by 3 is ...?

Answer 39

2

Answer 40

nope, follow the pattern please

Answer 41

x^2

Answer 42

good!

now what is 21x divided by 3?

Answer 43

7x

Answer 44

good!

now we divide the other side

132 divided by 3 = ?

Answer 45

44

Answer 46

good!

now we have

x^2 + 7x = 44

know what to do from here?

Answer 47

yea its 11

Answer 48

hold on a sec let me check my numbers

Answer 49

actually, no, x is not 11

Answer 50

do you know how to factor

x^2 + 7x = 44?

Answer 51

unless you were saying that the height is 11?

Answer 52

yes thats supposed to be

Answer 53

ok, may i ask how you got 11 as your height? (i'm not saying you're wrong i just want to make sure you understand)

Answer 54

i finished your problem