Question
The altitude of a triangle is three-fifth the length of its corresponding base. If the altitude is increased by 4 cm and the base is decreased by 2 cm, then the area of the triangle remains the same. Find the base of the triangle in cm.
Answer: Option C
:
C
Let the base of the triangle bexcm.
Then, the corresponding altitudeof the triangle would be3x5cm.
If altitude is increased by 4 cm,the new altitude=3x5+4cm
New base=x−2cm
Area of triangle=12×base×height
Since the area remains the same,12×x×3x5=12×(3x5+4)×(x−2)
⇒3x25=3x25+4x−6x5−8
⇒4x−6x5=8⇒20x−6x5=8
⇒14x=40
⇒x=4014=207⇒x=267cm
Hence, base of the triangle is267cmlong.
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:
C
Let the base of the triangle bexcm.
Then, the corresponding altitudeof the triangle would be3x5cm.
If altitude is increased by 4 cm,the new altitude=3x5+4cm
New base=x−2cm
Area of triangle=12×base×height
Since the area remains the same,12×x×3x5=12×(3x5+4)×(x−2)
⇒3x25=3x25+4x−6x5−8
⇒4x−6x5=8⇒20x−6x5=8
⇒14x=40
⇒x=4014=207⇒x=267cm
Hence, base of the triangle is267cmlong.
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