A Parallelogram Meets An Equilateral Triangle

Geometry Level 2

Find the area of the shaded(yellow) part.

25√3 35√3 all wrong 40√3

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9 solutions

Bryan Sangtania
Apr 9, 2014

BE=BF=EF= 10+2 = 12. So, FG=FH=GH= 2. Height of ABCD = height of BEGH = √12^2 - 6^2 - √2^2 - 1^2 = 6√3 - √3 = 5√3. The area of BEGH = 1/2 (12+2) 5√3 = 35√3. The area of ABCD = 15 x 5√3 = 75√3. So, the area of shaded orange = 75√3 -35√3 = 40√3

Area Of BEGH = (Area Of Triangle BEF) - (Area of Triangle HGF) = (1/2(12) 6√3 ) - (1/2 (2) √3 ) = 35√3
Area Of Triangle BCH = (Area Of BEGC ) - (Area Of BEGH) = (12*5√3) - (35√3) = 25√3 Area Of AEGD = 3 * 5√3 = 15√3 Area Of Yellow Parts = (Area Of BCH) + ( Area Of AEGD) = 25√3 + 15√3 = 40√3 ^_^

Mohamed El-Shaaer - 7 years, 1 month ago

good sir

Ravi Bendi - 7 years, 2 months ago

thnks.. good sir

Humayun Khan - 7 years, 2 months ago

AE = AB-AE = 15 - 12 = 3 cm > AE = DG EG = EF - EG = 12 - 2 = 10 cm >AD = EG = BC = HB

Triangle HBC is an equilateral triangle Area of HBC = [√3/4]x10x10 = 25√3

Parallelogram ADGE can be divided into 2 triangles Area of Triangle ADE = Area of Triangle DGE

Area of Parallelogram ADGE = [10 x 3 x sin(60)] = 15√3

Shaded Area = 25√3 + 15√3 = 40√3

Answer = 40√3

Peter Jake Araneta - 7 years, 1 month ago

Good

Pradip Babar - 7 years, 1 month ago

I THINK IT IS 69.28 SQUARE UNITS.

Domark Paquibot - 7 years, 1 month ago

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40 √ 3 = 69.28

Bryan Sangtania - 7 years, 1 month ago

A=bh, h=perpendicular from d, b=line segment AB=15....., m/_DAB=60degrees=>h=2 AD/root of 3=20/root 3 Area=15 20/root 3=100*root 3...... please verify your answer

Anuj Modi - 7 years, 1 month ago

I was wondering why triangle FGH is equilateral....the answer is due to similarity of triangles.This also means any equilateral triangle lopped of by a line parallel to the base of the original would be automatically equilateral.

Amit Chopra - 7 years, 1 month ago

150-.5 12 6 1.732+.5 2*1.732=??

Mohammed Nahas N - 7 years, 1 month ago

I forgot just the shaded orange...

Kughan Ravindran - 7 years, 1 month ago

AE = AB-AE = 15 - 12 = 3 cm > AE = DG EG = EF - EG = 12 - 2 = 10 cm >AD = EG = BC = HB

Triangle HBC is an equilateral triangle Area of HBC = [√3/4]x10x10 = 25√3

Parallelogram ADGE can be divided into 2 triangles Area of Triangle ADE = Area of Triangle DGE

Area of Parallelogram ADGE = [10 x 3 x sin(60)] = 15√3

Shaded Area = 25√3 + 15√3 = 40√3

Answer = 40√3

Mayank Chaurasia - 7 years, 1 month ago

Why is stated that ABCD is a parallelogram or that FG = FH = GH = 2 if it was never stated that AB and DC were parallel lines?

Dani Roja - 3 weeks, 5 days ago

Why BEGH= 1/2 (12+2) 5√3

Mohamed El-Shaaer - 7 years, 1 month ago

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5√3 is the height of the parallelogram, and (12+2) / 2 is to get the average of the bases of the trapezoid (FG = 12 and FG - EG = 2 and since the triangle is equilateral by similar triangles, the bases are 12 and 2) to get the gray area overlapping the parallelogram.

Pulga Martinez - 7 years, 1 month ago
Vishnudatt Gupta
May 17, 2014

BE=BF=EF= 10+2 = 12. So, FG=FH=GH= 2. Height of ABCD = height of BEGH = √12^2 - 6^2 - √2^2 -

1^2 = 6√3 - √3 = 5√3. The area of BEGH = 1/2 (12+2) 5√3 = 35√3. The area of ABCD = 15 x 5√3 =

75√3. So, the area of shaded orange = 75√3 -35√3 = 40√3

Antony Diaz
Apr 21, 2014

Y e l l o w a r e a s i s a p a r a l l e l o g r a m a n d a n e q u i l a t e r a l t r i a n g l e . F i r s t , w e k n o w t h a t D A B = G E B = 60 . A n d t h a t A D = E G = C B = B H = 10 c m . T h e n , w e c a l c u l a t e h e i g h t o f p a r a l l e l o g r a m A B C D . h = 10 × sin D A B = 5 3 . T h e n , w e k n o w t h a t o n e s i d e o f F E B i s 12 c m a n d A B i s 15 c m , s o A E = 3 c m . S o t h e a r e a o f A D G E i s ( 3 ) × ( 5 3 ) a n d t h e a r e a o f t r i a n g l e B H C i s ( 10 ) × ( 5 3 ) . F i n a l l y , t h e a r e a o f y e l l o w p a r t i s F E B + A D G E = 40 3 . Yellow \quad areas \quad is \quad a\quad parallelogram\quad and\quad an\quad equilateral\quad triangle.\quad First,\quad we\quad know\quad that\quad \angle DAB=\angle GEB=60\cdot .\quad And\quad that\quad AD=EG=CB=BH=10cm.\quad Then,\quad we\quad calculate\quad height\quad of\quad parallelogram\quad ABCD.\\ h=10\times \sin { \angle DAB } =5\sqrt { 3 } .\quad Then,\quad we\quad know\quad that\quad one\quad side\quad of\quad \triangle FEB\quad is\quad 12cm\quad and\quad AB\quad is\quad 15cm,\quad so\quad AE=3cm.\quad So\quad the\quad area\quad of\quad ADGE\quad is\quad (3)\times (5\sqrt { 3 } )\quad and\quad the\quad area\quad of\quad triangle\quad BHC\quad is\quad (10)\times (5\sqrt { 3 } ).\\ Finally,\quad the\quad area\quad of\quad yellow\quad part\quad is\quad \triangle FEB+ADGE=40\sqrt { 3 } .\\

Vijay Gupta
Apr 21, 2014

height of parallelogram = 10 x sin60 area of parallelogram = 150 x Sin60

area of full triangle = 1/2 x 12 x 12Sin60 = 72 x sin60

area of top secton of triangle = 1/2 x 2 x 2 sin60 = 2 x sin60

area of triangle inside parallelogram = 70 sin60

area of yellow part = 80 sin60

Ayush Kumar
Apr 18, 2014

by simple method of area we can calculate the answer which is equal to 40*3^1/2

Sumit Kumar
Apr 18, 2014

area of short parallelogram 15 3^(1/2)+area of triangle BCH is 25 3(1/2) then total is 40*3^(1/2)

Leela Prasad
Apr 18, 2014

area of EGHB is 50root3; area of CHB(equilateral) is 25root3; area of EBF is 36root3; area(ADE+BHC) = area(BHC)+area(ADHB)-{area(EFB)-area(GHF)}

Krishanu Kumar
Apr 17, 2014

one first find the perpendicular distance b/w the two // lines AB and CD and then find the area from //gm formula bxh and 1/2 x b xh.

Pritam Waghode
Apr 17, 2014

INTERESTING

tnx buddy

Yasir Nawaz - 7 years, 1 month ago

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