Page 81, question number 31 A

V=square root

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=Vs(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 centimeter. 
A) 15cm, 12cm, 10cm
B) 9.3cm, 11.4cm, 7.5cm

A= Vs(s-a)(s-b)(s-c)
A= Area
a, b, c= side lengths 
S= Half of the perimeter 

15+12+10=37
=37/2
=18.5

 V 18.5(18.5-15)(18.5-12)(18.5-10)

 V 18.5(3.5)(6.5)(8.5) V 18.5(22.75)(8.5) V 18.5(193.375) V 3577.4375 =59.81168364If you round off 59.81168364 to the nearest tenth, it would be 59.8cm.


A) 15cm, 12cm, 10cm is the right answer.

Textbook page 61, number 15 A

15) In dry air, the temperature decreases by about 0.65 degrees Celsius for each 100-m increase in altitude.

A)The temperature in Red Deer, Alberta, is 10 degrees Celsius in a dry air. What is the temperature outside an aircraft 2.8 km above the city?

0.65x28= 18.2

18.2-10= -8.2

The temperature outside an aircraft is -8.2 degrees Celsius.