CPhill

Not B

Note that we will have either   "H" or "T"  paired with  a number

Knowing this....what do you think ????

Here's the way I might do it, RP

1. Find the side lengths

2. Show that the diagonals have the same length

3. Show that the length  of any side = 

     diagonal length / √2

3. This will mean that we have a  square because the sides are congruent,  the diagonals are congruent and because of the proof of  (3),   they will meet at right angles

Which do you think it might be, NSS ??

Since AB = BC......the angles opposite those sides are equal   = x

So....angle B    =  180 - 2x

But....the sum of angles B and D =  (180 -2x) + 2x  =  180°

And when opposite sides of a  quadrilateral are supplementary [ sum to 180° ], the quadrilateral is a cyclic quadrilateral

We have 15 choices * 3 choices    =  45 choices

Thanks, heureka......!!!

[ I think we tried to make it more complicated than need be...!!!]

-5pi/ 6  =   -150”

2pi - 5pi/6 =

12pi/6 - 5pi/6 =

7pi/6   =  210°  

So....the refererence angle  is   [ 210 - 180]° = 30° in the 3rd quadrant

Here's a sketch

OK, Ant   .....!!!

Thanks, Ant !!!