Question

Question #4d964

Answer 1

`30`.

Explanation:

The Area `Delta` of a triangle having vertices

`(x_1,y_1), (x_2,y_2) and (x_3,y_3)` is given by,

`A=1/2|d|," where, "d=|(x_1,y_1,1),(x_2,y_2,1),(x_3,y_3,1)|`,

`=|(-1,-5,1),(4,-5,1),(4,7,1)|`,

`=-1(-5-7)-(-5)(4-4)+1(28-(-20))`,

`12+48`.

`rArr d=60`.

`:. Delta=1/2|60|=30`.