Yo sup??
15. Always true
we can say that an equilateral triangle is a special case of isosceles triangle. An isosceles triangle has two sides equal which is also true for an equilateral triangle which has 3 sides equal (hence two sides are also equal).
16.Sometimes true
A right triangle need not have two sides equal . For ex :
a triangle with sides 3,4 and 5 is a right triangle but none of its 2 sides are equal.
Whereas there are some cases when the two sides can be equal . For ex:
a triangle with sides 7,7 and 7√2 is an isosceles right angles triangle.
Hope this helps.