A slate is 35 cm long and 20 cm wide. It is surrounded by a wooden frame of width 2.5 cm all around it. Find the area of the wooden frame.

Question

Homework question I need help on... 

Answer 1

This question can be solved in several ways. Here is one way.

 

The Area of the larger rectangle (slate + frame) - Area of the slate will equal the Area of the frame.

 

we know that the Area of a rectangle = Length x Width

 

So, the Area of the larger rectangle = 40cm x 25cm (remembering that there are two sides to the frame)

 

AL = 40cm x 25cm = 1,000cm²

 

the Area of the slate is 35cm x 20cm = 700cm²

 

therefore, the Area of the frame = 1000cm² - 700cm² = 300cm²

 

Proof: the frame is made of 4 pieces; 2 are 20cm x 2.5cm, and 2 are 40cm x 2.5cm

2(20cm x 2.5cm) + 2(40cm x 2.5cm) = 100cm² + 200cm² = 300cm²