Find The Angle

Geometry Level 5

Let A B C \triangle ABC be an acute angled triangle. Let A 1 , B 1 , C 1 A_1, B_1, C_1 be the midpoints of B C , C A , A B BC,CA,AB respectively. The internal angle bisector of C 1 A 1 B 1 \angle C_1A_1B_1 intersects lines A B AB and A C AC at points A 2 , A 3 A_2, A_3 respectively. Let M A M_A and N A N_A be the circumcenters of B C A 2 \triangle BCA_2 and B C A 3 \triangle BCA_3 respectively. Points M B , N B , M C , N C M_B, N_B, M_C, N_C are defined analogously. It turns out that lines M A N A , M B N B , M C N C M_AN_A, M_BN_B, M_CN_C are concurrent at a point X X within A B C . \triangle ABC. Given that A B C = 3 0 , B C A = 4 5 \angle ABC = 30^{\circ}, \angle BCA= 45^{\circ} and k = A B + B C + C A X A + X B + X C , k=\dfrac{AB+BC+CA}{XA+XB+XC}, find 100 k . \left \lfloor 100 k \right \rfloor.

Details and assumptions
- The floor function x \left \lfloor x \right \rfloor denotes the largest integer x . \leq x. For example, 4.3 = 4 , π = 3. \left \lfloor 4.3 \right \rfloor = 4, \left \lfloor \pi \right \rfloor= 3.
- You might use a scientific calculator.
- A picture will accompany soon.
- GeoGebra users will be prosecuted.


The answer is 144.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Ahmad Saad
Nov 29, 2015

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...