Answer:
20.8 cm
Step-by-step explanation:
Perimeter of square = 4a
Dimension of the thumb print = 1 cm by 1cm
Perimeter of the size of the square (thumb print) = 4 × 1
= 4 cm
We are told in the question that:
The cellphone unlocks when the perimeter reaches 32 centimeters, taking a total of 2.5 seconds.
Hence,
32cm - 4cm = 28cm
What is the perimeter of the square after 1.5 seconds?
We set up a proportion
Time / perimeter
= 1.5/x = 2.5/ 28
Cross Multiply
= 2.5x = 1.5 × 28
x = 1.5 × 28/2.5
x = 16.8.
Therefore, the perimeter of the square after 1.5 seconds
= 16.8cm + perimeter of the square before expansion.
=16.8 cm + 4 cm
= 20.8 cm
