Reflection Theory (2 Viewers)

[Implying]

equiangular =/= congruent

PQ was common. they were congruent

 

[SImon05089]

i think hup meant equiangular as in 3 equal angles, pq is a side

 

[4025808]

well I was lucky, because I just used it
thank god for this question

 

[khfreakau]

You could have stated the perpendicular from the vertex to the base bisects the base in an isos triangle. Much quicker

yeah this, i did it using this method. i think i was lucky in that i remembered what the reflection property was, they rarely ask for those obscure dot points.

 

[zhuang281]

Only got this question because i learnt what the reflection theory was in physics.

 

[clementc]

How did you know it was an isosceles triangle though?

 

[khfreakau]

How did you know it was an isosceles triangle though?

altitude which bisects the base of a triangle means that it is isosceles.

 

[clementc]

but arent you trying to prove that the altitude bisects the triangle base?

 

[khfreakau]

but arent you trying to prove that the altitude bisects the triangle base?

oh right my bad i used this result for part ii, not i haha. in i i equated the tans of the angles to show that they were equal, and then said in ii that altitude which bisects the base means the triangle is isosceles, so PR=SP

 

[clementc]

fml of course .__. ohhh now seems so obvious lol