For problem 101, you put at the top of the triangle, use and for the legs, and use , or as the base. This way, and will be equal. Then, there is only one shape you can get, and all of them will be congruent, using by the angle-side-angle principle.
The rays of light are reflected by the mirror such that the perpendicular to the mirror bisects the angle between the light ray and it's reflection.
To indicate the visual field you have to construct the reflection of the complete room. Corresponding rays are drawn in the same colour. Thick lines indicate real light beams, thin line the reflection of the light beams.
Don't forget to answer the question!