Just take a photo of a cross and create a post with the tag geometrychallenge.
You can post your entry here in the comments but you must create a post for your own blog.

Also, make sure you follow the rules :)

Rules:

• The title of your post MUST be Geometry Challenge - Week # - Entry #
• Each contestant can only have 3 entries
• First tag of your post MUST be geometrychallenge
• You MUST only use your own original photography (all images will be checked for plagiarism)
• You MUST upvote this main post
• You MUST resteem this main post to help promote the challenge

The shape changes each week.

Good luck :)