## Semi-circle perimeter

Finding the perimeter of semi-circles using the formula $\large~P\,=\,\frac{\pi~d}{2}\,+\,d$.

 What is the perimeter of a semi-circle with a diameter of 8cm?

To answer this question, we need to realize that the figure is just half of a circle. This means we will still be using the formula . However, there will be a twist in what we do, because the formula gives us the circumference of a complete circle.

You will solve this problem using three steps: find the circumference of a full circle with the same diameter, divide that circumference in half, and then add the diameter.

 Example 1 What is the perimeter of a semi-circle with a diameter of 8cm? Step 1: Find the circumference of the full circle. Step 2: Divide the circumference in half. This is the length of just the curvy part of the semi-circle. Step 3: Add the diameter. 12.56 + 8 = 20.56 cm This is the perimeter of the semi-circle!

 Example 2 Find the perimeter of this quarter circle.

 Example 3 A wire is bent to form three semicircles. Find the length of the wire in terms of .

# Semi-circle circumference – CLASSWORK

Solve each of the following problems.

 Find the perimeter of this shape. Find the perimeter of this shape.

# Self-Check

 Question 1   A rope is arranged to form two semi-circles as shown. Find the length of the rope in terms of π. [show answer]

 Question 2 A garden is in the shape of a quarter circle. Find its perimeter. [show answer]

 Question 3 A circle is drawn inside a square. Find the circumference of the circle. [show answer]
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8004831075668335, "perplexity": 344.20594907662155}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-22/segments/1558232259452.84/warc/CC-MAIN-20190526185417-20190526211417-00222.warc.gz"}