How would you prove that the triangle below is equilateral? idk how to add pics, the pic is just a equilateral triangle show all angles to be congruent. show two sides are of equal measure. show at least two sides to be congruent. show all sides to be congruent.

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations