Answer: https://www.coursehero.com/file/36434863/math-124docx/
<u><em>Step-by-step explanation: In this WEB you will research for your answer you just need to Signed up i think so </em></u>
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<u><em>If you need help ask me</em></u>
$48
Here's how I found it ( just in case )

According to given figure, The Triangle BDC is a right angled Triangle (Angle D = 90°)
So, we can apply Pythagoras theorem to find the Side a (Hypotenuse)
Now, let's solve ~
Therefore, Length of side a is 5 units ~