Triangles The Invaders!

Geometry Level 2

Help! "Semicircle" country is invaded by so many right-angled triangles! The army of the "Semicircle" country need your help. They said: "∠AJH=156° and AJ=JH. ∠BAG and ∠BHG are separated into 5 equal parts. Their weakest part is at ∠DAH. If we able to determine the angle, we could destroy them immediately!" So, help them to determine ∠DAH.


The answer is 51.6.

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.

2 solutions

Raymond Lin
Jun 29, 2014

Since triangle A J H AJH is isosceles, J A H = J H A = 12 \angle JAH = \angle JHA = 12 .

Since A J H \angle AJH and B J A \angle BJA are supplementary, B J A = 24 \angle BJA = 24 ,

Since B J A \angle BJA and B A J \angle BAJ are complementary (they are the non-right angles of right triangle B A J BAJ ), B A J = 66 \angle BAJ = 66 .

Since B A J = B A G \angle BAJ = \angle BAG is divided in 5 5 equal parts, and D A J \angle DAJ is 3 5 \frac{3}{5} of B A J \angle BAJ , D A J = 39.6 \angle DAJ = 39.6 .

D A H = D A J + J A H = 39.6 + 12 = 51.6 \angle DAH = \angle DAJ + \angle JAH = 39.6+12=\fbox{51.6} .

Above point J there are two more points, let's call point K and L where L is higher than K. We can see that angle ALH is about half of 156 which is 78. Because sum angle of triangle is always 180 and angle DAH and EHA is both same(in triangle ALH) so angle of DAH is 51

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...