Can You Solve This Maths Problem? - Find The Total Area

Can you solve this maths problem by finding the total shaded area of the two semicircles? This is a question from the 2010 senior maths challenge question 23. For more senior maths challenge videos check out the following links below 2017 challenge questions 1-10 https://www.youtube.com/watch?v=eW5-Z24JfRU&t=127s 2017 challenge questions 11-20 https://www.youtube.com/watch?v=uO7n4j1vJcc&t=72s 2017 challenge questions 21-25 https://www.youtube.com/watch?v=UnJWM0IpIsg&t=1220s DON'T FORGET TO SUBSCRIBE AND FEEL FREE TO ASK ANY QUESTIONS IN THE COMMENT SECTION BELOW