We can use Pythagorean's Theorem in order to find the remaining side length a^2+b^2=c^2 Let a be the shadow length Let b be the height of the flagpole Let c be the hypotenuse 28^2+b^2=35^2 784+b^2=1225 b^2=1225-784 b^2=441 b=√441 b=21 Therefore the flagpole is 21 meters tall. Hope this helps!