An isosceles triangle is a triangle that has one pair of equal sides. The Formula in finding the perimeter of a triangle is PΔ=S₁+S₂+S₃. Since two legs are missing, and the given are the base and perimeter, we will use the formula : S₁+S₂ = PΔ-S₃, where: S₁+S₂ are the legs and <span>S₃ is the base. Substitute values: </span><span>S₁+S₂ = 43cm - 7 cm </span> = 36 cm since S₁ and S₂ are equal, divide 36cm by 2. Therefore S₁ and <span>S₂ measures 18cm. Check: </span><span>PΔ=S₁+S₂+S₃ </span><span> = 18cm + 18 cm + 7cm = 43cm
