Convert first 10 cm to feet. . so we will have same unit for each sides.

Given:

10 cm = 0.33 feet

8 feet

12 feet

Perimeter of triangle = a + b + c

= 0.33 feet + 8 feet + 12 feet

= 20.33 feet

However you can also change it to all cm.

Convert 8 feet and 12 feet to centimeters.

Given:

10 cm

8 feet = 243.84 cm

12 feet = 365.76 cm

P = 365.76 cm + 10 cm + 243.84 cm

= 619.6 cm