On 27/07/2013 14:15, Tim Streater wrote:
In article ,
Ramsman wrote:

On 27/07/2013 11:54, Tim Streater wrote:

Well if it slopes 15deg then the angle it makes with the wall is
90-15 =
75deg. So if it extends out Z (which you say is 1m to 4m), then that's
the hypotenuse of the triangle in which case the vertical height of the
triangle is given by:

H / Z = cos 75

So:

H = Z * cos 75

But you said the front edge is up by 2.1m so that gives you:

X = 2.1 + H

or X = 2.1 + (Z * cos 75)

if Z=2 then I type this into Google:

2.1 + (2 * cos (75 deg))

and it gives me 2.617....


No need for a spreadsheet at all.

Here's the diagram

.
|\
| \
| \
| \ Z
| \
|H \
| \
| \
| \
.---------.
|
|
|
|
| 2.1
|
|
|


My understanding is that 2m is the horizontal distance ('it extends
out Z'), so it's different from that.

|\
| \
| \
| \
| \
|X-Y \
| \
X| 15\
---------
| Z
|
|
| Y
|
|
|

(X-Y)/Z = tan 15
.
.
.
X = Y + Z (tan 15)

Spreadsheet with Y in A1, Z in B1, then C1 is
=A1+(B1*TAN(RADIANS(15))) which gives 2.64 for the given values.

Well, only Our Dave knows whether the Z refers to the length of material
that has unrolled from the sunroof (my interpretation) or refers to the
horizontal distance extended (your interpretation).

Either way, once you have the formula, no spreadsheet is needed. I just
typed my formula straight into Google and it gave me the answer.


As we were always told at school, read the question. TMH said 'I want to
make up a spreadsheet to calculate this for any height "Y" and any
extension.' Hence my reply and my formula.

--
Peter