In an isosceles triangle ABC, the base of AC is 7cm and the perimeter is 17cm. find the side of AB

Let us write down the formula by which we find what the perimeter of a given isosceles triangle ABC is equal to.
P = AB + BC + AC.
Since an isosceles triangle is given, its sides AB and BC are equal.
Hence, it is possible to write down.
P = 2AB + AC.
2AB = P – AC.
AB = (P – AC): 2.
Now let’s substitute the values of P and AC into this formula, then calculate the length of AB.
AB = (17 – 7): 2.
AB = 10: 2.
AB = 5 (cm).
Answer: 5 cm is the length of the side AB.