Here's the solution,
The given triangle is an <u>equilateral triangle</u>, because it's all angles measure 60° each
now,
Area of an equilateral triangle :
=》

where,
=》

=》

=》

or
=》

She used 180 beads because 45x4 =180
A because it is a pattern 4 6 4 8 and that is why it is a