SSAT Upper Level Math : How to find the perimeter of a parallelogram

Study concepts, example questions & explanations for SSAT Upper Level Math

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Example Questions

Example Question #1 : How To Find The Perimeter Of A Parallelogram

The base length of a parallelogram is \(\displaystyle 4t+6\) which is two times more than its side length. Give the perimeter of the parallelogram in terms of \(\displaystyle t\).

Possible Answers:

\(\displaystyle 12t+9\)

\(\displaystyle 12t+18\)

\(\displaystyle 10t+18\)

\(\displaystyle 8t+9\)

\(\displaystyle 6t+9\)

Correct answer:

\(\displaystyle 12t+18\)

Explanation:

The side length is half of the base length:

\(\displaystyle h=\frac{w}{2}=\frac{4t+6}{2}=\frac{4t}{2}+\frac{6}{2}=2t+3\)

The perimeter of a parallelogram is:

\(\displaystyle Perimeter=2(w+h)\)

Where:


  \(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length

 

\(\displaystyle =2[(4t+6)+(2t+3)]\)

\(\displaystyle =2(6t+9)\)

\(\displaystyle =12t+18\)

Example Question #2 : How To Find The Perimeter Of A Parallelogram

The side length of a parallelogram is \(\displaystyle t^2+1\) and the base length is three times more than side length. Give the perimeter of the parallelogram in terms of \(\displaystyle t\).

Possible Answers:

\(\displaystyle 8t^2+8\)

\(\displaystyle 8t^2\)

\(\displaystyle 4t^2+8\)

\(\displaystyle 4t^2+4\)

\(\displaystyle 8t^2+4\)

Correct answer:

\(\displaystyle 8t^2+8\)

Explanation:

The base length is three times more than the side length, so we have:

 

Base length \(\displaystyle =3(t^2+1)=3t^2+3\)

 

The perimeter of a parallelogram is:

\(\displaystyle 2(w+h)\)

Where:

\(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length. So we get:

\(\displaystyle Perimeter=2(w+h)=2\left [ (3t^2+3)+(t^2+1) \right ]\)

\(\displaystyle =2(4t^2+4)\)

\(\displaystyle =8t^2+8\)

Example Question #1 : How To Find The Perimeter Of A Parallelogram

The base length of a parallelogram is 10 inches and the side length is 6 inches. Give the perimeter of the parallelogram.

Possible Answers:

\(\displaystyle 34\)

\(\displaystyle 16\)

\(\displaystyle 32\)

\(\displaystyle 30\)

\(\displaystyle 60\)

Correct answer:

\(\displaystyle 32\)

Explanation:

Like any polygon, the perimeter of a parallelogram is the total distance around the outside, which can be found by adding together the length of each side. In case of a parallelogram, each pair of opposite sides is the same length, so the perimeter is twice the base plus twice the side length. Or as a formula we can write:

 

\(\displaystyle Perimeter=2(w+h)\)

Where:

\(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length. So we can write:

 

\(\displaystyle Perimeter=2(w+h)=2(10+6)=32\)

 

Example Question #1 : How To Find The Perimeter Of A Parallelogram

The base length of a parallelogram is \(\displaystyle t+2\). If the perimeter of the parallelogram is 24, give the side length in terms of \(\displaystyle t\).

Possible Answers:

\(\displaystyle 22-2t\)

\(\displaystyle 10+t\)

\(\displaystyle 10-t\)

\(\displaystyle 20+t\)

\(\displaystyle 20-t\)

Correct answer:

\(\displaystyle 10-t\)

Explanation:

Let:

Side length \(\displaystyle =x\).

The perimeter of a parallelogram is:

\(\displaystyle 2w+2h\)

where:

\(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length. The perimeter is known, so we can write:

 

\(\displaystyle Perimeter=24=2(t+2)+2x\)

 

Now we solve the equation for \(\displaystyle x\):

 

\(\displaystyle 24=2(t+2)+2x\)

\(\displaystyle \Rightarrow 24=2t+4+2x\)

\(\displaystyle \Rightarrow 24-2t-4=2x\)

\(\displaystyle \Rightarrow 20-2t=2x\)

\(\displaystyle \Rightarrow 10-t=x\)

 

Example Question #2 : How To Find The Perimeter Of A Parallelogram

The base length of a parallelogram is identical to its side length. If the perimeter of the parallelogram is 40, give the base length.

Possible Answers:

\(\displaystyle 10\)

\(\displaystyle 20\)

\(\displaystyle 16\)

\(\displaystyle 8\)

\(\displaystyle 5\)

Correct answer:

\(\displaystyle 10\)

Explanation:

The perimeter of a parallelogram is:

\(\displaystyle 2(w+h)\)

Where:

\(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length. In this problem the base length and side length are identical, that means:

\(\displaystyle w=h\)

So we can write:

\(\displaystyle Perimeter=40=2(w+w)\Rightarrow 20=2w\Rightarrow w=10\)

Example Question #841 : Geometry

The base length of a parallelogram is \(\displaystyle 2t+3\) and the side length is \(\displaystyle 2t-3\). Give the perimeter of the parallelogram in terms of \(\displaystyle t\) and calculate it for \(\displaystyle t=1\).

Possible Answers:

\(\displaystyle 8t, 8\)

\(\displaystyle 6t+6, 12\)

\(\displaystyle 6t, 6\)

\(\displaystyle 8t+8, 16\)

\(\displaystyle 4t, 4\)

Correct answer:

\(\displaystyle 8t, 8\)

Explanation:

The perimeter of a parallelogram is:

\(\displaystyle 2(w+h)\)

where:

\(\displaystyle w\) is the base length of the parallelogram and \(\displaystyle h\) is the side length. So we have:

 

\(\displaystyle Perimeter=2(w+h)=2\left [ (2t+3)+(2t-3) \right ]=2(4t)=8t\)

and:

\(\displaystyle t=1\Rightarrow 8t=8\times 1=8\)

Example Question #1061 : Ssat Upper Level Quantitative (Math)

Parallelogram1

The above parallelogram has area 100. Give its perimeter.

Possible Answers:

\(\displaystyle 20+20\sqrt{2}\)

\(\displaystyle 20+20\sqrt{3}\)

\(\displaystyle 40\sqrt{2}\)

\(\displaystyle 40\sqrt{3}\)

\(\displaystyle 40\)

Correct answer:

\(\displaystyle 20+20\sqrt{2}\)

Explanation:

The height of the parallelogram is \(\displaystyle BD\), and the base is \(\displaystyle DC\). By the \(\displaystyle 45^{\circ}-45^{\circ}-90^{\circ}\) Theorem, \(\displaystyle BD=CD\). Since the product of the height and the base of a parallelogram is its area, 

\(\displaystyle BD \cdot CD = A\)

\(\displaystyle \left (BD \right )^{2} = 100\)

\(\displaystyle BD = 10\)

By the \(\displaystyle 45^{\circ}-45^{\circ}-90^{\circ}\) Theorem, 

\(\displaystyle CD = AB = BD = 10\), and

\(\displaystyle AD = BC = BD \cdot \sqrt{2} = 10\sqrt{2}\)

The perimeter of the parallelogram is

\(\displaystyle AB + CD + BC + AD = 10 + 10 + 10\sqrt{2}+ 10\sqrt{2} = 20+20\sqrt{2}\)

Example Question #842 : Geometry

Parallelogram2

Give the perimeter of the above parallelogram if \(\displaystyle BD = 10\).

Possible Answers:

\(\displaystyle 40+20\sqrt{3}\)

\(\displaystyle 60\sqrt{2}\)

\(\displaystyle 40+40\sqrt{3}\)

\(\displaystyle 60\sqrt{3}\)

\(\displaystyle 40+20\sqrt{2}\)

Correct answer:

\(\displaystyle 40+20\sqrt{3}\)

Explanation:

By the \(\displaystyle 30^{\circ}-60^{\circ}-90^{\circ}\) Theorem:

\(\displaystyle AB = CD= BD\sqrt{3}= 10\sqrt{3}\), and

\(\displaystyle AD=BC= 2\cdot BD = 2\cdot 10 = 20\)

The perimeter of the parallelogram is

\(\displaystyle AB + CD + BC + AD = 20+20+ 10\sqrt{3}+ 10\sqrt{3} = 40+20\sqrt{3}\)

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