Find the length of side ab. give your answer to 1 decimal place.12 cm62"

One unique triangle, because those angles add up to 180, and that's how many degrees there are in one triangle.

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)