# Math Help - find length of hypotenuse

1. ## find length of hypotenuse

how can i find the length of the hypotenuse in the attached image assuming i know the length of side a + all 3 angles?

also how would i find it if i knew the length of side b + all 3 angles?

2. Originally Posted by .paul.
how can i find the length of the hypotenuse in the attached image assuming i know the length of side a + all 3 angles?

also how would i find it if i knew the length of side b + all 3 angles?
$a = \cos (30deg) \times c$

$b = \sin (30deg) \times c$

and

$\frac{a}{\sin (30deg)} = c$

3. ## formula

Originally Posted by aidan
$a = \cos (30deg) \times c$

$b = \sin (30deg) \times c$

and

$\frac{a}{\sin (30deg)} = c$

that nearly works. heres a clearer image of what i'm trying to do. the first red line is at the 12 o'clock position. the second red line is supposed to be from the centre to the 1'oclock position ending at the 2nd rectangle

heres the calculations i'm using:

'351,151 - centre
'10 + sf.Height - 2nd rectangle top
'30 degrees - 1 o'clock
Dim a As Single = (151 - (10 + sf.Height))
Dim lX2 As Single = 351 + Math.Sin(Math.PI * 30 / 180) * (a / Math.Sin(30))
Dim lY2 As Single = 151 - Math.Cos(Math.PI * 30 / 180) * (a / Math.Sin(30))

4. Originally Posted by .paul.
how can i find the length of the hypotenuse in the attached image assuming i know the length of side a + all 3 angles?

also how would i find it if i knew the length of side b + all 3 angles?

to find c ---use - cos30= 107/c
c = 107/cos30
c = 123.6

you can usee - cosx= adjecent side/ hypotenuse
sinx = oposite side/ hypotenuse
then rearrange the eqation to find hypotenuse

you can also find it if you have side b and any 2 angles exept the right angle which is 90deg by using thos formula ===sin30 = b/c