Try yo work out where the image of the triangle will be first before you reveal the answer.[br]Move point D or E to move the line. Move a, B or C to change the shape of the triangle.

You can use the "polygon tool" to draw a triangle where you think the reflection will be. Click "Show Reflection" to check your drawing.[br][br]Use refresh to return to the start. Drag the points to move the triangle and the line and try different variations.