Thread: Finding the lengths and sides of a kite

Hello, Please advise if I have worked this lot out correctly.

I have included a diagram to help explain what I am trying to do.

Looking at the kite I require to find the length of the side BC. Apart from the angles included the only other information I was given is the length of the diagonal, which is 40cm

I used the following idea

a / sinA = b / sinB

a / sin 25 = 40 / sin 100

a = 40 sin 25 / sin 100

a = 16.90 / 0.985 = 17.2 cm (3 sf)

BC = 17.2 cm. This is the hypotenuse of the right hand lower triangle in the kite.

I was asked to add a second diagonal BD and label the intersection. I know what an intersection is, but what do they mean by asking label it?

Do they mean; ABD?

I am required to find the length of the diagonal BD.

This is what I did.

I used the sin rule because when I look at the lower right hand side triangle, it is a right angle triangle and I have the angle opposite, so

sin 50 x 17.2 = 13cm

so the opposite side of the triangle length is 13cm

I then used pythagoras to find the length of the adjacent side

c = square root a^" - b^2

17.2^2 - 13^2 = 11.3 cm

Because I am asked for the length BD I have doubled it to 22.5 (3 sf)

Please advise if I have worked it out OK

Thanks

David

Here are two very good webpages on the kite shape.

PAGE ONE

PAGE TWO

Thanks for the web pages, very well explained about kites, but no maths working out?

Originally Posted by David Green

but no maths working out?

But that is your job.

Originally Posted by Plato

But that is your job.

I agree, and I did it in my first thread, would of just liked a second professional opinion from somebody with more experience than I.

David