Look at the following rectangle:
BC = 8
BD = 17
Calculate the area of the rectangle ABCD.
We have hundreds of course questions with personalized recommendations + Account 100% premium
Look at the following rectangle:
BC = 8
BD = 17
Calculate the area of the rectangle ABCD.
We will find side DC by using the Pythagorean theorem in triangle DBC:
Let's substitute the known data:
Let's take the square root:
Now we have the length and width of rectangle ABCD and we'll calculate the area:
120
Look at the rectangle ABCD below.
Side AB is 6 cm long and side BC is 4 cm long.
What is the area of the rectangle?
The diagonal isn't a side of the rectangle! Area requires length × width, not diagonal × side. The diagonal helps you find the missing side using the Pythagorean theorem.
Look for the diagonal - it's always the hypotenuse! The two sides that meet at a corner (like BC and CD) are the legs of the right triangle formed by the diagonal.
Check your arithmetic! In geometry problems, side lengths are always positive. If you get negative under the square root, you made a calculation error.
Only when you're given a diagonal and need to find a missing side. If you already know both length and width, just multiply them directly!
Substitute back into the Pythagorean theorem: ✓
Get unlimited access to all 18 Pythagorean Theorem questions, detailed video solutions, and personalized progress tracking.
Unlimited Video Solutions
Step-by-step explanations for every problem
Progress Analytics
Track your mastery across all topics
Ad-Free Learning
Focus on math without distractions
No credit card required • Cancel anytime