Answer:
(√6)/2 square units
Step-by-step explanation:
The area of a triangle is half the magnitude of the cross product of the vectors representing adjacent sides.
QR = (4-3, -1-(-4), -4-(-5)) = (1, 3, 1)
QS = (3 -3, -5-(-4), -6-(-5)) = (0, -1, -1)
The cross product is the determinant ...
The magnitude of this is ...
|QR × QS| = √((-2)² +1² +(-1)²) = √6
The area of the triangle is half this value:
Area = (1/2)√6 . . . . square units