I calculated tan and sin (theta) for a physics lab experiment -- two-slit interference

Question

I had to use this equation y = L tan (theta), with
y = 0.25 and L = 2 and tan (theta) came out to be 7.12 in degrees and 0.1243 in radians.

I found sin (theta) by using the triangle for
X^2 + Y^2 = R^2

Sin (theta) (0.25/2.01) = 7.14 in degrees and 0.1246 in radians.

Now, I have to find the percent error made when you replace the sin by the tangent leading to this equation

d(Y/L) = nλ, or
Y/n = (L/d)λ

I don't know how to do this, I'm extremely confused

Answer 1

For small angles, sin theta is approximately equal to tan theta = Y/L
= 0.25/2

Calculate the error (0.25/2.01 - 0.25/2)/(0.25/2.01)