A Bit of Mathmatical help

[born2trot]

its over 2 decades since i've been to school!!!

Lets get the whipper snappers onto it Graham:confused1:

[Kev Stephenson]

390

 

Pythagorus therum

 

80 squared - 20 squared = the distance from the point of the triangle to half way along the 40 meter length = 77.46m (approx 78m)

 

Now calculate the number of trees in a 78m line = 39 trees and there would be 10 lines in a 20m rectangle giving 390 trees in total

[NFG]

If each side is 80m & one is 40m then the land forms an isosceles triangle.

 

The area of an isosceles triangle is half base * height - but the height is not 80m!

 

To calculate the height you need to drop a line from tip to base & use C=A/H from SOHCAHTOA so Cos(some angle) = 20/80 or .25

 

So use ACos of .25 = 75.5224878 degrees as the angle at each side of triangle

 

The height can be calculated by ATan 75.5224878 = O/A or

 

A Tan 75.5224878 = 3.87298334

3.87298334 * 20 = 77.4596668 lets say 77.5

 

so the land area is actually (40 * 77.5)/2 = 1550 sq meters

 

= reaches for coat - asbestos one to protect from flames - but it looks right to me!

[born2trot]

I knew i went wrong somewhere!!!

[headgroundsman]

well done all those who realised the height is not 80

390 is close enough

[Kev Stephenson]

If each side is 80m & one is 40m then the land forms an isosceles triangle.

 

The area of an isosceles triangle is half base * height - but the height is not 80m!

 

To calculate the height you need to drop a line from tip to base & use C=A/H from SOHCAHTOA so Cos(some angle) = 20/80 or .25

 

So use ACos of .25 = 75.5224878 degrees as the angle at each side of triangle

 

The height can be calculated by ATan 75.5224878 = O/A or

 

A Tan 75.5224878 = 3.87298334

3.87298334 * 20 = 77.4596668 lets say 77.5

 

so the land area is actually (40 * 77.5)/2 = 1550 sq meters

 

= reaches for coat - asbestos one to protect from flames - but it looks right to me!

 

But he didn't ask for the area?????

[firewood]

390

 

Pythagorus therum

 

80 squared - 20 squared = the distance from the point of the triangle to half way along the 40 meter length = 77.46m (approx 78m)

 

Now calculate the number of trees in a 78m line = 39 trees and there would be 10 lines in a 20m rectangle giving 390 trees in total

 

 

 

 

correct.

[likeitorlumpit]

390

 

Pythagorus therum

 

80 squared - 20 squared = the distance from the point of the triangle to half way along the 40 meter length = 77.46m (approx 78m)

 

Now calculate the number of trees in a 78m line = 39 trees and there would be 10 lines in a 20m rectangle giving 390 trees in total

 

correct