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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## What is the length of AD? tagged by: swerve ##### This topic has 1 expert reply and 0 member replies ### Top Member ## What is the length of AD? What is the length of AD? $$A.\ \ 2\sqrt{10}$$ $$B.\ \ 4\sqrt{10}$$ $$C.\ \ 2\sqrt{5}$$ $$D.\ \ 4\sqrt{5}$$ $$E.\ \ \sqrt{10}$$ The OA is A. Please, can any expert explain this PS question for me? I tried to solve it but I'm not sure and I can't get the correct answer. I need your help. Thanks. ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Top Reply Quote: What is the length of AD? $$A.\ \ 2\sqrt{10}$$ $$B.\ \ 4\sqrt{10}$$ $$C.\ \ 2\sqrt{5}$$ $$D.\ \ 4\sqrt{5}$$ $$E.\ \ \sqrt{10}$$ The OA is A. Please, can any expert explain this PS question for me? I tried to solve it but I'm not sure and I can't get the correct answer. I need your help. Thanks. Hi swerve, Let's take a look at your question. Draw a horizontal line parallel to CB, from point D that intersects the line Ab at point E, such that AED is a right triangle. Since, $$DE=CB$$ Therefore, $$DE=6$$ Now, let's find AE. $$AE=AB-EB$$ $$AE=AB-DC$$ $$AE=12-10$$ $$AE=2$$ Now, we can find AD using Pythagoras Theorem, $$AD=\sqrt{\left(AE\right)^2+\left(DE\right)^2}$$ $$AD=\sqrt{\left(2\right)^2+\left(6\right)^2}$$ $$AD=\sqrt{4+36}$$ $$AD=\sqrt{40}$$ $$AD=2\sqrt{10}$$ Therefore, option A is correct. Hope it helps. I am available if you'd like any follow up. _________________ GMAT Prep From The Economist We offer 70+ point score improvement money back guarantee. Our average student improves 98 points. Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now. • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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