# Finding the angle for an isosceles triangle roof

I am using clips to make a roof shaped like an isosceles triangle.

This feels like one of those things that would be trivial with physical LEGO bricks, but it is near impossible with Stud.io.

How can I calculate the angle that the roof needs to be at for the clip to hold the bar piece?

You are trying to assemble a triangle with inclined parts of 8 units in length and horizontal line is 7 units. The rest is math:

`∠α = cos⁻¹(3,5÷8) = 64.0555°`

Due to slight imperfection in LEGO assembly you can easily take a value of 64° for one side and 296° (you were close!) for another.

I did a mock-up in LDCad and proved that it works with angle of 64°, as you can clearly see below:

To get the exact answer, this is what high school geometry and trig is useful for in the real world :)

Alternatively, switch off collision detection and just try changing the angles in small increments (e.g. 1 degree) until it looks right. Type the angle into the box shown in the picture, don't try to rotate the parts with the mouse.

Then switch collision detection on again to check if you were close enough.