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.
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
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