Monday, November 19, 2012

Textbook question 31 a)

31.

The area of a triangle can be determined using Heron's formula, which requires the side lengths of the triangle.
Heron's formula is A=√s(s-a)(s-b)(s-c). In the formula A is the area; a,b and c are the side lengths; and s is half the perimeter or a+b+c.
                                                          2
Determine the area of each triangle with the following side lengths. 
                                  
Express each area to the nearest tenth of a square centimetre.

a) 15cm, 12cm, 10cm

A=√s(s-a)(s-b)(s-c)

A=area

a,b,c=side lengths

s= half the perimeter  

-------------------------------------------------

15+12+10=37 

                =37/2

                =18.5

√18.5(18.5-15)(18.5-12)(18.5-10)

 

√18.5(3.5)(6.5)(8.5)

 

√18.5(22.75)(8.5)

 

√18.5(193.375)

 

√3577.4375

 

A= 59.81168364 

we have to round it to the nearest tenth of a square centimetre. 

so it's going to be 59.8cm2 

 

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