Question

Find the area of a rectangular field with dimensions (4a + 5b) units and (4a – 5b) units, if a=12m and b=5m.(using identities)

Answer 1

Answer:

Area of the rectangular field is 1679m²

Explanation:

Dimensions of the field: ( 4a + 5b ) and (4a – 5b)

Area of a rectangle = Length × Breath ( Product of dimensions )

Area = ( 4a + 5b ) × (4a – 5b)

identity: ( a + b ) ( a - b ) = a² - b² [ here 4a and 5b corresponds with a and b respectively ]

Area = ( 4a )² - ( 5b )²

Substitute the value of a and b as 12 meters and 5 metres respectively.

Area = { 4(12 m ) }² - { 5(5 m ) }²

Area = ( 48m )² - ( 25m )²

Area = 2304m² - 625m²

Area = 1679m²