### Home > GB8I > Chapter cc46 > Lesson cc46.4.2 > Problem 6-139

Plot Δ

*MJN*on graph paper with points*M*(3, 3),*J*(1, 1), and*N*(6, 1). 6-139 HW eTool (Desmos). Homework Help ✎Rotate the triangle 90º counterclockwise (↺) about the origin. Name the coordinates of Δ

*M*′*J*′*N*′.Next, reflect Δ

*M*′*J*′*N*′ across the*y*-axis. Name the coordinates of*M*″*J*″*N*″.What is the area of Δ

*MJN*?

Use the eTool to complete the transformation. Notice how the points have changed. Pay attention closely to point *N*.

Notice that the *y-* coordinate has been multiplied by −1 and the *x-* and *y-*coordinates are interchanged.

Use the eTool. Notice how the coordinates compare to the coordinates of Δ*M''J''N''*. What happens to the points when you translate across the *y*-axis?

*M''*(3, 3), *J''*(1, 1), *N''*(1, 6)

What is the length of the base, *JN*? What is the height from point *M* to base *JN*? Use the area formula for triangles.

Use the eTool below to solve the problem.

Click the link at right for the full version of the eTool: INT1 6-139 HW eTool