How do i solve this without a calc;
$\displaystyle Area=\frac{1}{2}\times\sqrt2\times\sqrt2\times(\fr ac{\sqrt2}{2})$
I'm having a problem when i can't cancel the -2 and the cosB, for example;
From the cosine rule to find the area of a triangle:
$\displaystyle -2\times(x+1)\times(x-2)\times{Cos120}$
$\displaystyle -2\times(x+1)\times(x-2)\times-\frac{1}{2}$
Here i can just cancel the $\displaystyle -2$ and $\displaystyle -\frac{1}{2}$ as $\displaystyle -2 \times 1 \times -\frac{1}{2} = 1$
The problem arises when i cant cancel these two components so what do i do? For example;
$\displaystyle Area=\frac{1}{2}\times5\sqrt3\times{10}\times(-\frac{\sqrt3}{2})$