Which triangle has an irrational number as one of its side lengths?

Option 4

Step-by-step explanation:

The square root of 25 is 5 so it is not number 1

The root of 400 is 20 so it is not number 2

the square root of 676 is 26 so it not that.

That leaves option four which is irrational

b. an equilateral triangle inscribed in a circle

step-by-step explanation:

we are given the figure of two circles having a triangle inside.

now, we know that,

"when a figure is lying inside an another figure, then the outside figure is known as circumscribed figure and the figure lying inside is referred to as the inscribed figure".

as we see that, the circles are containing the triangle completely.

thus, the circles are the circumscribed figures and the triangle is the inscribed figure.

hence, we get, 'an equilateral triangle is inscribed in a circle'.