Area Problem #16

dec2

A regular pentagon and a square both share a side with a regular decagon. The green shape is made from the vertices of the square and pentagon. If the side length of the decagon is 2cm, what is the area of the green shape?

Advertisements

8 thoughts on “Area Problem #16

    • I’m afraid not. It should work out to very, very close to 4cm^2. So close in fact, that I convinced myself I’d found a new ‘thing’ and that it was perfectly equal to the area of the square. It’s not perfectly equal to the square, but it is extremely close in area.

  1. Of course it is! Mine was the area of the trapezium and I forgot to subtract the triangle which was sqrt(10+2sqrt5)/2 so I am getting now 3.996982634 cm^2. Thanks.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s