1. ## Quick question

How do i solve this without a calc;

$Area=\frac{1}{2}\times\sqrt2\times\sqrt2\times(\fr ac{\sqrt2}{2})$

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:

$-2\times(x+1)\times(x-2)\times{Cos120}$

$-2\times(x+1)\times(x-2)\times-\frac{1}{2}$

Here i can just cancel the $-2$ and $-\frac{1}{2}$ as $-2 \times 1 \times -\frac{1}{2} = 1$

The problem arises when i cant cancel these two components so what do i do? For example;

$Area=\frac{1}{2}\times5\sqrt3\times{10}\times(-\frac{\sqrt3}{2})$

3. anyone?