Triangle Area

Since $5^2 + 12^2 = 25 + 144 = 169 = 13^2$ , thus we have a right angled triangle with base lengths of 5 and 12.

Hence, the area of the triangle is $\frac {1}{2} \times 5 \times 12 = 30$ .

Area=1/2 base height = 1/2x12x5 =1/2x60 =60/2 =30

i honestly didnt find this to be a brilliant.org type question, it doesnt involve as much thought as many of their other questions.

If one understands the relationship between the triangle and rectangle, the only formula you have to remember is the area of rectangle = l x w - and the "divided by, half of" just makes sense for the area of [the] triangle. More conceptual understanding and sense-making than just another formula to memorize...

Which we can see,the triangle is right angled. So the area of the triangle is 1/2 5 12=30

It's 30, you add all the lengths, :P Easy.....