Question

Galina is finding the area of triangle RST. To do so, she follows the steps in the table.

Answer 1

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

$A_{ABCT}=4\cdot 3=12$ sq. un.

3 step:

$A_{\triangle ART}=\dfrac{1}{2}AR\cdot AT=\dfrac{1}{2}\cdot 2\cdot 3=3$ sq. un.

$A_{\triangle BRS}=\dfrac{1}{2}BR\cdot BS=\dfrac{1}{2}\cdot 2\cdot 2=2$ sq. un.

$A_{\triangle SCT}=\dfrac{1}{2}CS\cdot CT=\dfrac{1}{2}\cdot 1\cdot 4=2$ sq. un.

4 step:

$A_{\triangle RST}=A_{ABCT}-A_{\triangle ART}-A_{\triangle BRS}-A_{\triangle SCT}=12-3-2-2=5$ sq. un.

Answer: in step two you write dimensions of rectangle ABCT: length 4 units and width 3 units. Correct choice is B.

Answer 2

A rectangle is drawn around the triangle with a measurement 3 unit × 4 unit. The graph is shown below