Please help?

PQRS is a cyclic quadrilateral with

Question

Please help?

PQRS is a cyclic quadrilateral with <PSR = 80˚, PS = 22 cm, QR = 32 cm and SR = 40 cm.
Find correct to 2 decimal places the area of triangle PQS.

I found myself that PQ = 22.46 cm as well.
Thanks!

anonymous · Answer

attachment

anonymous · Answer

Also if it helps... I found the area of PQRS to be 787.29 cm^2

mayankdevnani · Answer

@amriju    plz help...

amriju · Answer

no...u r  not sure that the unknown angles r 90...can u use trigo...properties of triangles..?

amriju · Answer

yeah @mayankdevnani

mayankdevnani · Answer

wht?

amriju · Answer

plz help whom..?

mayankdevnani · Answer

@sedighn   yaa...

anonymous · Answer

The previous question regarding that cyclic quadrilateral was to find the area of PQRS which is 787.29 cm^2 which I got correct. I'm unsure how to find the area of triangle PQS though :O

amriju · Answer

do u know properties of triangles?

anonymous · Answer

Yes... well it must be solved using the sine and cosine rules but I just don't know how to start doing it

anonymous · Answer

How to start solving the question, I mean

amriju · Answer

|dw:1352026063120:dw|...ok...have u found QS?..if not..try this way.. see the triangle..? cos A=(b^2+c^2-a^2)/2bc...now determine cos P nd cos R  this way...both will involve the use of QS..( so draw it)...both values ( of cos P nd cos R) are equal but different sign..since P+R=180...nd cos(180-x)=-cos x...from the two eqns determine QS...u have all the three sides...determine any angle of the triangle..and find the area...use absinx....

amriju · Answer

there may be a betr way....so wait for some more tym nd see if anyone else replies...

anonymous · Answer

Thanks a lot @amriju :)