TRIGONOMETRY (Questions)
ANSWERING QUESTIONS
In any question ALWAYS follow these steps:
1. If necessary, draw the diagram
2. Locate the right angle and the other angle
3. Locate the two sides which are relevant to the question (there will only be 2) and label them O, A or H.
4. Use SOHCAHTOA to help you decide which of sin, cos or tan you will need to use - if you have O and H use sin (SOH), if you have A and H use cos (CAH) and if you have O and A use tan (TOA).
5. Use the SOHCAHTOA Triangles or Substitution (FIS) to solve the question.
Eg. Using SOHCAHTOA Triangles.
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step 1: |
Draw diagram
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steps 2, 3: |
The side marked x is touching the 60 degree angle so label it Adj (A).
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The side marked 12 cm is the one which the right angle is pointing at so label it Hyp (H).
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Step 4: |
A and H means use cos (CAH). Draw a copy of the cos triangle:
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Step 5: |
We are asked to find x (Adj) so cover this up with your finger on the cos triangle:
This leaves just the Cosθ next to the H. Remember if they are next to each other, multiply them:
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Eg. Using substitution (FIS – Formula, Input, Solve)
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step 1: |
Draw diagram
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steps 2, 3: |
The side marked x is touching the 60 degree angle so label it Adj (A).
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The side marked 12 cm is the one which the right angle is pointing at so label it Hyp (H).
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Step 4: |
A and H means use cos (CAH)
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Step 5 (substitution - FIS): |
(Formula) (Input) (Solve)
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