Question

Distance between A (2, -1) and (2,a) is 4 units. Find the value of a where a is positive.

Answer 1

a = 3

Explanation:

Calculate the distance d using the distance formula and equate to 4

d =
`\sqrt{(x_(2)-x_(1))^2+(y_(2)-y_(1))^2 }`

with (x₁, y₁ ) = (2, - 1) and (x₂, y₂ ) = (2, a)

d =
`√((2-2)^2+(a+1)^2)` =
`√(0+(a+1)^2)` =
`√((a+1)^2)` = a + 1 then

a + 1 = 4 ( subtract 1 from both sides )

a = 3