# Maths question trig?

Watch
Announcements
Thread starter 6 years ago
#1
Abcd is a rectangle and I need to find out the value of x when the length is 18 cm and the width is 14cm (bottom)
It has two diagonal lines inside te rectangle dividing it into 4 triangles one labelled x
0
Thread starter 6 years ago
#2
Theres a photo attached
0
6 years ago
#3
(Original post by Forevereuphoria)
Theres a photo attached
No there's not.
0
Thread starter 6 years ago
#4
(Original post by mackemforever)
No there's not.
There is now
0
Thread starter 6 years ago
#5
Image is attached
0
6 years ago
#6
(Original post by mackemforever)
No there's not.
Yes there is.

I'll take a look.
0
Thread starter 6 years ago
#7
Image is attached
0
6 years ago
#8
(Original post by Forevereuphoria)
Theres a photo attached
What have you tried so far? Can you take a picture of your working and we can see where you need to go next?
0
Thread starter 6 years ago
#9
An image is attached
0
6 years ago
#10
(Original post by Forevereuphoria)
Theres a photo attached
X= angle CXD
tanC = 18/14
Length BD=length AC (use Pythagoras)
Divided by two, that length is equal to DX
you can then use the sin rule sinX/14 = sinC/Length DX to find x

actually, that seems a lot for 3 marks, there's probably a better way
0
Thread starter 6 years ago
#11
(Original post by shutupem)
X= angle CXD
tanC = 18/14
Length BD=length AC (use Pythagoras)
Divided by two, that length is equal to DX
you can then use the sin rule sinX/14 = sinC/Length DX to find x

actually, that seems a lot for 3 marks, there's probably a better way
I still dont understand could you explain what you are talking about i.e why its tan? Put examples in
0
Thread starter 6 years ago
#12
Image is attached for both please explain
0
6 years ago
#13
(Original post by Forevereuphoria)
I still dont understand could you explain what you are talking about i.e why its tan? Put examples in
What have you done so far?
0
6 years ago
#14
it's just 90 degree trig...SOHCAHTOA

PS your picture is upside down
0
Thread starter 6 years ago
#15
(Original post by Slowbro93)
What have you done so far?
Sorry didn't notice your question I've done nothing that looks correct so theres no point me posting it.
0
6 years ago
#16
(Original post by Forevereuphoria)
I still dont understand could you explain what you are talking about i.e why its tan? Put examples in
Opposite angles are equal, so x is angle CXD
ACD is a right angled triangle
You have 14 and 18, two sides which are not the hypotenuse.

You can work out the size of angle C, which is the same in the right angled triangle and in the triangle containing angle CXD, using SohCahToa.

The two sides you know he lengths of are the opposite and adjacent sides, relative to angle C, so you use tan(angle) = opp/adj.

If you knew the length of the hypotenuse, so you could do Pythagoras first instead of second, then you could use sin or cos. I did the SohCahToa first, so had to use tan as those were the only two sides I knew the length of.

Hope that helps.
0
Thread starter 6 years ago
#17
(Original post by shutupem)
Opposite angles are equal, so x is angle CXD
ACD is a right angled triangle
You have 14 and 18, two sides which are not the hypotenuse.

You can work out the size of angle C, which is the same in the right angled triangle and in the triangle containing angle CXD, using SohCahToa.

The two sides you know he lengths of are the opposite and adjacent sides, relative to angle C, so you use tan(angle) = opp/adj.

If you knew the length of the hypotenuse, so you could do Pythagoras first instead of second, then you could use sin or cos. I did the SohCahToa first, so had to use tan as those were the only two sides I knew the length of.

Hope that helps.
im still baffled...
0
6 years ago
#18
(Original post by Forevereuphoria)
im still baffled...
What about it is confusing?
0
Thread starter 6 years ago
#19
(Original post by shutupem)
What about it is confusing?
How are you labelling the sides...
is the answer 90
0
Thread starter 6 years ago
#20
Photo is attached
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Current uni students - are you thinking of dropping out of university?

Yes, I'm seriously considering dropping out (145)
14.38%
I'm not sure (43)
4.27%
No, I'm going to stick it out for now (302)
29.96%
I have already dropped out (26)
2.58%
I'm not a current university student (492)
48.81%