# Thread: Trigonometry help to find gamma angle

1. ## Trigonometry help to find gamma angle

Can anyone please help me with this, i've been working on it for ages and still can't seem to get the answer for gamma:

Assume that the frame and coupler can be up to 500 units long and the other two up to 300 units long, and include these rules in your validation checks.

Here is the Image: Untitled.jpg picture by Emmcee1 - Photobucket

Values available are the sides p, q, r, s and the crank angle θ. You can work out all coordinates easily once you know the rocker angle γ. This sequence of calculations can derive it:
1. Calculate d using the Cosine Rule in the lower triangle, since you know the opposite angle and the other two sides.
2. Calculate α using the Sine Rule.
3. Calculate β by applying the Cosine Rule to the upper triangle, re-arranging the formula to give the angle.
4. Obtain γ from the relation α + β + γ = 180°

I used the cosine and sine rule and pythagorus theorem but the final equations i get i get variables that are unknown.

This is what I have done so far to find the unknown angles:
d = (p^2 + q^2 -2pq cos(theta))^1/2
y = 180degress - alpha- beta
alpha = sin ^-1(q.sin(tetha)/d)
beta= cos^-1(-r^2+d^2+s^2/2ds)

any help will be appreciated

2. ## Re: Trigonometry help to find gamma angle

I am confused as of what you are looking for exactly... is it an expression for angle gamma?