Perimeter
XZ = sqrt ( 5^2 + 3^2) = sqrt (34)
XY = sqrt ( 4^2 + 5^2) = sqrt (41)
YZ = sqrt ( 9^2 + 2^2) = sqrt (85)
sqrt (34) + sqrt(41) + sqrt (85) ≈ 21.45 units.....correct !!!
The area is a little difficult.....there are several ways to do this using trig.....but....I'm going to assume you might not have had that.....so....let's do this
The slope between Y(4,-4), and Z(-5,-2) is (-2 - -4) / (-5 -4) = 2/-9 = -2/9
And the equation of the line joining these two points is y = (-2/9)(x - 4) - 4 →
y = (-2/9x + 8/9 - 4 → y = (-2/9)x - 28/9
So...... a perpendicular line from the apex of the triangle - point X - to this line will serve as the height of the triangle.....and the slope of this perpendicular line will be the negative reciprocal of -2/9 = 9/2
And the equation of this line will be
y = (9/2) ( x - 0) + 1 → y = (9/2)x + 1
Setting these lines equal, we can find the x coordinate of their intersection
(-2/9)x - 28/9 = (9/2)x + 1
-28/9 - 1 = (9/2 + 2/9)x
-37/9 = (85/18)x multiply both sides by 18/85
(-37/9)(18/85) = -74/85
And the y coordinate of their intersection can be found as (9/2)(-74/85) + 1 = -248/85
So the distance from X -(0,1)- to (-74/85, -248/85) is given by
sqrt [ (74/85)^2 + ( 1 + 248/85)^2 ] = 37/ sqrt (85) = the triangle's height
So.....the area of a triangle is (1/2) B * H
The Base is YZ = sqrt (85)....so the area =
(1/2)sqrt(85) * 37 / sqrt (85) - (1/2)(37) = 18.5 square units !!!
Whew!!!!....that was a lot of work......but....I verified the answer here :
http://www.wolframalpha.com/input/?i=area+triangle+%5B+(0,1),+(4,-4),++(-5,-2)%5D
Hope that helps !!!