Let the length of one of the diagonals be 2x and the other be 2y, then
cos (76/2) = x/10
x = 10 cos 38 = 7.88 cm
sin (76/2) = y/10
y = 10 sin 38 = 6.16 cm
It is

The equation for area of a trapezoid is

Substituting our values in

We can then simplify the expression

Answer:
At 43.2°.
Step-by-step explanation:
To find the angle we need to use the following equation:

Where:
d: is the separation of the grating
m: is the order of the maximum
λ: is the wavelength
θ: is the angle
At the first-order maximum (m=1) at 20.0 degrees we have:

Now, to produce a second-order maximum (m=2) the angle must be:


Therefore, the diffraction grating will produce a second-order maximum for the light at 43.2°.
I hope it helps you!
8 is 6.2
9 is 7
The pattern here is +0.8.
4.6 - 3.8=0.8
5.4-4.6=0.8, and so on