Trig – So far we have...

July 2011

Subject Content = Covered

We are working on applications

• Multistep and practical problems• 3 Dimensional problems• Setting out the steps in a logical and clear

manner, which may include drawing triangles• Remember: Similar triangles, angles in a

triangle add to 180 degrees and SOH-CAH-TOA and Pythag is ONLY for RIGHT ANGLE triangles!

Key Tips from studyit• Check that your calculator is in "degree" mode at the start of the exam. If your

calculator is in the wrong mode, you will get the wrong answers even if you do the correct working.

• If using a Graphics Calculator make sure you are in DEG mode. SETUP (SHIFT MENU) Scroll down to ‘Angle’ and check it says ‘Deg’. If not push F1 (Deg).

• Use appropriate rounding and units.• Round lengths using significant figures, for example, 'The distance is 360 metres

(2sf).'• Round angle measurements to 1 decimal place unless told otherwise, for

example, ‘The angle is 56.7 degrees (1dp).’• Do not round until the final step in your answer as this affects the accuracy of

your answer.• Check that your answer makes sense in the context of the question. If not, check

your working and method.• Show working to back up the steps you take to come to a solution.• Ensure you know how to use measuring equipment such as a measuring tape,

protractor, and clinometer.

Pythagoras c2 = a2 + b2

where c is the hypotenuse = the longest side

SOH-CAH-TOA

We talked about similar triangles = same angles = scale factor

3D Problems

SOH-CAH-TOA

Pythagoras c2 = a2 + b2 so c = (a2 + b2 )^0.5 a2 = c2 - b2 so a = (c2 - b2 )^0.5 b2 = c2 - a2 so b = (c2 - a2 )^0.5

How to label a triangle

• H = Hypotenuse, which is always opposite the right angle and always the longest side. It does not move, Pythag: H2 = O2 + A2

• O = opposite which is the side opposite the angle we are interested in.

• A = Adjacent which lies between the right angle and the angle we are interested in.

Which formulae do I use?

Pythag or SOH-CAH-TOA

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Practical measurementUsing a Clinometer

3D Problem Solving

Today:Algebra recap

solve for xax2 + bx + c = 0

Working on problems in the text book and work book.

One group at a time measuring the classroom as per yesterday.

solve for xax2 + bx + c = 0

The

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Quad Formula from http://users.rcn.com/mwhitney.massed/quadratic_formula_proof.html

Ms Allan’s Wiki:

http://2011maths.wikispaces.com/NCEA+Level+1+Trig