1 step: to draw a rectangle around triangle RST, you should
- draw points A(-1,-1), B(-1,3) and C(2,3);
- connect points A, B, C and T consecutively.
2 step: rectangle ABCT has length AB=4 units and width BC=3 units. Then
[tex]A_{ABCT}=4\cdot 3=12[/tex] sq. un.
3 step:
[tex]A_{\triangle ART}=\dfrac{1}{2}AR\cdot AT=\dfrac{1}{2}\cdot 2\cdot 3=3[/tex] sq. un.
[tex]A_{\triangle BRS}=\dfrac{1}{2}BR\cdot BS=\dfrac{1}{2}\cdot 2\cdot 2=2[/tex] sq. un.
[tex]A_{\triangle SCT}=\dfrac{1}{2}CS\cdot CT=\dfrac{1}{2}\cdot 1\cdot 4=2[/tex] sq. un.
4 step:
[tex]A_{\triangle RST}=A_{ABCT}-A_{\triangle ART}-A_{\triangle BRS}-A_{\triangle SCT}=12-3-2-2=5[/tex] sq. un.
Answer: in step two you write dimensions of rectangle ABCT: length 4 units and width 3 units. Correct choice is B.
