Find the base of an isosceles triangle if it is 3 cm larger than the lateral side and the perimeter of the triangle is 30.

Suppose the lateral side of the specified triangle will be equal to the variable a.

Then, according to the condition of this problem, the base of this triangle can be represented as a + 3.

Since from the condition of this problem we know for sure that the perimeter of this geometric figure is 30 centimeters, then it will be possible to write down the equation and find out what is the length of the base:

a + a + a + 3 = 30;

3a = 27;

a = 9;

9 + 3 = 12.

Answer: Under such initial conditions, the base length will be 12 cm.