ABC is an isosceles triangle , right angled at C. From C draw CD so that angle BCD = 30 ° and angle ACD 120 ° , and from B draw BD perpendicular to CD at D. If CA = CB = a show that AD = a/2(7+2*3^(1/2))^1/2.

You have 2 sides that are 2 cms and you have 6 sides that are 1/2 cm and you have 4 sides that are 1 cm. the smallest sides are 1/2 the medium sized sides are 1 and the smallest are 1/2. so to find the perimeter you have to add them all up together so your answer will be 11 cm's