To use the ASA Congruence Theorem, you have to copy a side, then two angles. A straightedge and a compass are required for this.
Practice makes perfect
To copy the triangle using the ASA Congruence Theorem, we have to copy two angles and the side that's in between these angles.
Let's start by copying the base of â–³ DEF. To do that, we will draw a straight line directly underneath â–³ DEF that is longer then DF.
To copy the length of DF we set the compass to measure DF on â–³ DEF. Having measured the length of DF, we will use the same compass setting to measure that exact distance on our segment and erase whatever is leftover.
Next, we have to copy the angles, ∠D and ∠F, from △ DEF. To do that, we draw identical arcs around G, I, D and F like below.
Let's measure the angle on the original and copy it so that ∠D ≅ ∠G. Knowing the direction of GH, we go ahead and draw what's going to be our second side. Make it a long line!
We will repeat the procedure for ∠F and ∠I before drawing the third side, IH, until it hits GH.
Finally, we will erase whatever is left over of GH.
