Explanation:
An isosceles triangle has 2 sides that are the same.
A scalene triangle has all different sides.
If the scalene triangle has a right angle, you can use:
A = ½ bh
where b is the base and h is the height
If you know one of the angles, you can use:
A = ½ ab sin C
where a and b are the sides and C is the angle between them.
Otherwise, you can use Heron's formula:

where a, b, and c are the sides.