1.) Simplity - 2(4m - 7)
2 answers:
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Answer:
The length of the diagonal = 3.6 feet
Step-by-step explanation:
* Lets change the story problem to equation to solve it
- Diagonal in a rectangle is the line which joining two
opposite vertices in it
- The diagonal , the length and the width formed together right
angle triangle where the diagonal is the hypotenuse of the
triangle and the length, the width are the two legs of the
right angle
- The length of the diagonal d is √(l² + w²) ⇒ Pythagoras theorem
∴ d² = l² + w²
- The diagonal is 2 feet more than the width
∴ d = w + 2
- The length is twice the width
∴ l = w
* Lets substitute the value of d and l in the equation of Pythagoras
∴ (w + 2)² = (2w)² + w² ⇒ solve the bracket
∴ w² + 4w + 4 = 4w² + w² ⇒ collect them in one side and add like term
∴ 4w² + w² - w² - 4w - 4 = 0 ⇒ add the like term
∴ 4w² - 4w - 4 = 0 ⇒ divide all term by 4
∴ w² - w - 1 = 0 ⇒ solve the quadratic using the formula
- In ax² + bx + c = 0
∵ a = 1 , b = -1 , c = -1
∴
-The value of the width is 1.6 feet
∴ The length = 1.6 × 2 = 3.2 feet
∴ The length of the diagonal = 2 + 1.6 = 3.6 feet