Astandard yield sign is 20 inches on each side , what is the sign approximate area if it is an equilateral triangle

It is 6o inches all together because if you take 20 and add it three times because a triabgle has three sides then you will get 60

The angles in an equilateral triangle are all 60 degrees
and the altitude  will be  obtained from the equation

tan 60 = a / 10    where a = altitude and 1/2 base of triangle = 1/2 * 20 = 10

a = 10 tan 60 = 10 sqrt3

so the area = 10* 10 sqrt3 = 100 sqrt3 in^2

or 173 in^2  to neraest in^2