Question

Triangle RST, with vertices R(2,3), S(6,7), and T(4,8), is drawn inside a rectangle, as

shown below.
10
9
T
00
8
2
6
6
V
5
3
4
R
2
-2
-1
2
3
4
5
8
9
10
What is the area, in square units, of triangle RST?

Answer 1

Explanation:

The area of the larger rectangle is (4)(5)=20.

The area of the top left right triangle is (1/2)(2)(5)=5.

The area of the top right right triangle is (1/2)(2)(1)=1.

The area of the bottom right triangle is (1/2)(4)(4)=8.

So A = 20 - 5 - 1 - 8 = 15 - 9 = 6.