Formula for angles in an IF statement

[rtcwlomax]

Hey All,

Having a bit off a brain freeze on this.

I am try to create an IF statement that returns a value of true or false based on an angle calculation.

The statement will be IF Angle ABC < 180 Degrees returns True, else False.

I have attached a screenshot to help explain.

ax, bx, cx, ab & bc are variables. I hope this makes sense to some mathematician

ABC Angle.JPG


p.s. Mods I tried to edit typo in title!

[FDibbins]

What are your inputs?

Im thinking =if(A+B+C<180,TRUE,FALSE)

[rtcwlomax]

My inputs are in lengths:

ac (horizontal line)
ab (horizontal line)
bx
ax
cx

[rtcwlomax]

IF (ax + cx > bx, TRUE, FALSE)

Edit: on second thoughts that is wrong!

[shg]

The sign of the cross product tells you whether the rotation of AB onto BC is positive (your thumb points out of the screen) or negative (your thumb points into the screen) when you do a right-hand rotation:

Row\Col	A	B	C	D	E
1	Pt	x	y
2	A	0	0		B2:C4: Input
3	B	0.5	0.5
4	C	1	0
5
6	AB	0.5	0.5		B6: =B3-B2
7	BC	0.5	-0.5
8
9	AB x BC	-0.5			B9: =B6*C7 - C6*B7

[rtcwlomax]

Hey shg,

Brilliant thanks. Don't remember this from my school days but it works nicely.

[shg]

You're welcome.