Insane Area Chasing!

Geometry Level 4

In the adjoining figure A Q = 2 AQ = 2 Q B = 4 QB=4 B P = 3 BP=3 P C = 5 PC=5 C R = 6 CR=6 R A = 4 RA=4 Find the area of triangle PQR


The answer is 5.8.

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.

3 solutions

As noted by two friends below, ABC is 3-4-5 right angle at B.
So SinA=4/5, SinC=3/5.
So areas of triangles at ,
A i s 1 / 2 4 3 4 / 5 = 6 , . . . . . . . . . . B i s 1 / 2 2 4 4 / 5 = 16 / 5 , . . . . . . . . . . . C i s 1 / 2 6 5 3 / 5 = 9. A r e a A B C = 1 / 2 6 8 = 24. . S o t h e a r e a o f P Q R = 24 6 16 / 5 9 = 5.8 . A \ is \ 1/2*4*3*4/5=6,..........B \ is \ 1/2*2*4*4/5=16/5,...........C \ is \ 1/2*6*5*3/5=9. \\ Area \ ABC=1/2*6*8=24. \\. So \ the \ area \ of\ PQR=24-6-16/5-9=**5.8**.


Ramesh Goenka
Oct 25, 2014

one thing to note here is that the bigger triangle ABC is a right angle triangle (6,8,10) and hence all the included angles can be found out very easily. Now considering all the small triangles i.e. PRC, PQB, QAR, using the formula A= ( Sin(included angle)*product of containing sides)/2 , the areas are calculated and by subtracting them from the area of ABC we get the required answer.

Rifath Rahman
Nov 22, 2014

First,note that its sides are(6,8,10) which means its a right triangle.Now B=90,and sinC=(6/10) or C=37 and same way A=53.Using cosine law we can find out the sides of the triangle PQR. ie QR^2=2^2+4^2-2 4 2*cos(53)=10.37 or QR=3.22.Same way PR is 3.616 and QP=5(we can get it by pythagorean theorem too).We know all the sides of the triangle so we can compute the area with Heron's formula which becomes 5.8

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...