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mitchelsewbaran
What is the length of line BD in the equilateral triangle ABC shown below?
It says 10, right? In which case, do you know the 30-60-90 special triangle? |dw:1346612914460:dw| This triangle also half of an equilateral triangle. 2x is the 'diagonal' side of one half of your triangle, so 2x=10. Do you have it?
so the answer is 5, right?
the length of line BD
Not quite. The right angle is made from the perpendicular line dashed line in the middle of your equilateral triangle. You need to orient yourself so that the 30-60-90 triangle is the right half of your triangle. so the length of BD is represented by \[x \sqrt{3}\]