Working out - The smaller triangle is directly proportional to the bigger one. You can see that AD is two thirds bigger than AE, therefore BC needs to be two-thirds bigger than AB, and CD needs to be two-thirds bigger than BE.

Working out - The smaller triangle is directly proportional to the bigger one. You can see that AD is two thirds bigger than AE, therefore BC needs to be two-thirds bigger than AB, and CD needs to be two-thirds bigger than BE.

best solution so far. does make sense i suppose :thumbsup: repped

using trig you can work out angle BAE and AEB, ADC will be the same as AEB.

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

using trig you can work out angle BAE and AEB, ADC will be the same as AEB.

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

using trig you can work out angle BAE and AEB, ADC will be the same as AEB.

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

here may explain it easier given you know the above.

Been a long long time since I had to do this, but heres how you solve it:

* - Get ALL the angles of the top triangle (i.e. AB AE and BE)
* - Now since BE and CD are parallel they are also the same angles as the bottom two angles of the top triangle (i.e. AEB = ADC and ABE = ACD).
* - So you now have all the angles of the triangle and you can easily solve to find BC and CD.

Can't do pythagoras as there is no 90 degree angle.
I agree BC is 6cm as using ratios AE:ED is 12:8 = 3:2
As the large triangle is a enlargement of the small triangle with a centre of enlargement A, the ratio of AB:BC will be the same, so 3:2 becomes 9:6
Still using ratios AB:AC (also AE:AD and BE:CD) is 3:5 so 9.6 scales to 16cm as 9.6/3x5 is 16

Can't do pythagoras as there is no 90 degree angle.
I agree BC is 6cm as using ratios AE:ED is 12:8 = 3:2
As the large triangle is a enlargement of the small triangle with a centre of enlargement A, the ratio of AB:BC will be the same, so 3:2 becomes 9:6
Still using ratios AB:AC (also AE:AD and BE:CD) is 3:5 so 9.6 scales to 16cm as 9.6/3x5 is 16

## All Comments

(34) Jump to unreadPost a commentNote: BE and CD are parallel

thanks :?

I tried pythagoras but i thought i would need a 90 degree angle?

answers are nothing without working out

how did you get this buddy?

Incorrect 1 out of 10

please try harder

Incorrect again

Detention next time. :-D

please try harder

Detention next time. :-D

please explain! how i've done it seems right to me...

CD is Compact Disc

HTH

best solution so far. does make sense i suppose :thumbsup: repped

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

it would be embarrassing if not - should be getting an A at A-Level in the summer...

A D =20 so 20 sq add 15 sq = 625 which the squzreroot is 25 therfore CD = 25

I loved that, exactly what I'd have found myself doing in the middle of an exam! :oops:

working out?

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

I'll try this approach- thanks :) repped

A D =20 so 20 sq add 15 sq = 625 which the squzreroot is 25 therfore CD = 25

This is pythagoras but there is no 90 degree angle? :thinking:

You then have 1 length and 2 angles of the large triangle, I am sure you can then work out the other sides from that (don't have anything to do it myself)

here may explain it easier given you know the above.

use this to find the angles of the top triangle

http://www.teacherschoice.com.au/maths_library/trigonometry/solve_trig_sss.htm

and this to find the angles / sides of the large one

http://www.teacherschoice.com.au/Maths_Library/Trigonometry/solve_1.gif

* - Get ALL the angles of the top triangle (i.e. AB AE and BE)

* - Now since BE and CD are parallel they are also the same angles as the bottom two angles of the top triangle (i.e. AEB = ADC and ABE = ACD).

* - So you now have all the angles of the triangle and you can easily solve to find BC and CD.

Heres the weblink:

http://www.college-cram.com/study/trigonometry/presentations/304

Easy peasy.

I agree BC is 6cm as using ratios AE:ED is 12:8 = 3:2

As the large triangle is a enlargement of the small triangle with a centre of enlargement A, the ratio of AB:BC will be the same, so 3:2 becomes 9:6

Still using ratios AB:AC (also AE:AD and BE:CD) is 3:5 so 9.6 scales to 16cm as 9.6/3x5 is 16

I agree BC is 6cm as using ratios AE:ED is 12:8 = 3:2

As the large triangle is a enlargement of the small triangle with a centre of enlargement A, the ratio of AB:BC will be the same, so 3:2 becomes 9:6

Still using ratios AB:AC (also AE:AD and BE:CD) is 3:5 so 9.6 scales to 16cm as 9.6/3x5 is 16

well said.

some people are over thinking this...

SOHCAHTOA can't remember how you do it though....

2. Use Cosine Rule to find A,B,E

3.Use Sine rule to find CD and Sine Rule for AC-9cm

BC=6 CD=16