Meg described four triangles as shown below:

triangle p: all sides have length 7 cm.
triangle q: two angles measure 55°.
triangle r: two sides have length 8 cm, and the included angle measures 60°.
triangle s: base has length 8 cm, and base angles measure 55°.

which triangle is not a unique triangle?

The triangle which is not a unique triangle is:

                   Triangle Q.

                  Hence, Triangle P will be unique.

     Hence, Triangle Q is not unique.

( Since we are given two angles and the measure of the third angle could be known with the help of property that:

Sum of all the angles of a triangle is 180° )

( Since, we make a line segment of given length and then keep the compass at one of end point and make a 60 degree angle and cut that side into length 8 cm and finally join the other end point and the constructed line to get a triangle)

Hence, Triangle R is also unique.

( First draw a line segment of length 8 cm and at both the ends of the line make a 50 degree angle and extend the line over the arc of the angle and see where two lines intersects.

By such a way we obtain a unique triangle)

your answer would be b

step-by-step explanation: