Geometry

bhars18 · **Geometry -** 25-04-2003, 09:18 AM

What is the area of a parallelogram with an angle 45 degrees, height 4 cm and a diagonal 5 cm?

Regards,
Bharathi

P.S: Please post your answers in the thread only after 6 PM., April 25 2003.

**MavericK** · **Re: Geometry -** 25-04-2003, 10:07 AM

Quote:

Originally Posted by bhars18

What is the area of a parallelogram with an angle 45 degrees, height 4 cm and a diagonal 5 cm?

longest diagonal??

bhars18 · **Re: Geometry -** 25-04-2003, 10:27 AM

Quote:

Originally Posted by anil

longest diagonal??

That is the problem

Bharathi.

**MavericK** · **Re: Geometry -** 25-04-2003, 10:30 AM

Quote:

Originally Posted by bhars18

Quote:

Originally Posted by anil

longest diagonal??

That is the problem

well well...if it is..then the answer is simple

so guess it isn't

bhars18 · 25-04-2003, 10:33 AM

Quote:

Originally Posted by anil

well well...if it is..then the answer is simple so guess it isn't

Shouldn't the answers be simple

?

Quote:

Originally Posted by santosh

Questions can never be silly.. however answers can

Bharathi

**MavericK** · 25-04-2003, 10:34 AM

Quote:

Originally Posted by bhars18

Shouldn't the answers be simple

?

i meant the shortest diagonal is 5

Andy · 25-04-2003, 10:54 AM

post edited by anil.. Junta plzz stick to the rules of the Quizmaster

and plzz post the answers only after the deadline

CatCrazy · 25-04-2003, 11:49 AM

hey andy ,

no answers bfor 6 pm april 25th

dont want to make life easy or hard for any one

**MavericK** · **Re: Geometry -** 25-04-2003, 06:07 PM

Quote:

Originally Posted by bhars18

What is the area of a parallelogram with an angle 45 degrees, height 4 cm and a diagonal 5 cm?
P.S: Please post your answers in the thread only after 6 PM., April 25 2003.

Here I am

so now the 1st thing abt the qn is that it hasnt been mentioned abt which diagonal is 5cm...so if we take the longer one as 5 units...after calculations we get the angle b/w the diagonal and base as tan-1 (inverse) of 4/3...which is not equal to 22.5 deg..which it is supposed to be...hence the shorter diagonal is 5...hence it makes the problem easier

and the answer's the same as Andy posted b4..28 sq.cm

bhars18 · 25-04-2003, 06:20 PM

tan-1(4/3) is good...

My approach : (as usual complicated

)
Name ||gm ABCD base AB angle DAB = 45.

Dropping perpendicular from D to meet AB at E, we get AE = 4cm. (isoceles triangle ADE)

Assume AC=5cm. Drop perpendicular from C to meet AB extended at F. Right triangle hypotenuse=5, height=4 => AB + BF = 3cm

But AE itself is 4cm. So assumption AC=5 is wrong. So it cannot be AC. Only BD = 5.

EB = 3 (pyth. triplet) AB=7 ED=4

Area of ||gm = base * height = 4*7 = 28 sq cms.

Bharathi.

Tip: Parallelograms on the same base and between same parallel lines have the same area.