David Lang wrote:

Hi

I'm building a pergola for my sister in law and my grasp of maths is failing
me.

The roof is an isosceles triangle, e.g. two sides the same and a base.

The angle at the apex is 140 degrees and the two base angles 20 degrees. I
know the size of the base.

How do I calculate the length of the two identical sides and the height from
base to apex?

I seem to recall something about "some officers have, curly auburn hair,
till old age" but I think that only applies to a right angle triangle.

Dave


An isocelese triangle is two right angled ones stuck together, conceptually.

YOU work it out.

I can't work out how a single triangle can actually form a roof at all...