Thursday, June 6, 2013

Finding the length of a side

// trigonometry lesson #5


this is the calculator recommended for this lesson (fx82au PLUS) 


hey world! today we'll be learning to find the length of a side of a right-angled triangle. So lets get started!!



Step 1: Remember to label the triangle! H (hypotenuse), O (opposite) and A (adjacent).
Step 2: Choose whether sin, cosine or tangent should be used.
Step 3: Write an equation or formula using the correct ratio.
Step 4: Make the pro numeral the subject.
Step 5: Use a calculator to find or evaluate the answer.

Here is an example:

Example:
Find the value of the pro numeral in this right-angled triangle, correct to two decimal places.



Solution:
SOH, CAH or TOA?
Use cos because A (adjacent side) and H (hypotenuse) are marked.

          cos 50 (degrees) =  adjacent 
                                    hypotenuse
          cos 50 (degrees) =          y       
                                      hypotenuse
cos 50 x 8 =    y   x 8          (mulitply both sides by 8)
                     8
8 cos 50 = y
          y = 8 cos 50
             = 5.142300877...
          y = 5.14                  (round of to 2 d.p)



judy, hannah & paul

No comments:

Post a Comment