How to use the triangle method to solve for an unknown..

How to put formulas into the triangle.

The ‘signs’ of the triangle.

What is the unknown?

What are the other two units?

Solving math problems on the Science TAKS.

How to solve for an unknown using the “reverse the sign” method.

How to solve for an unknown using the “cross multiply” method.

Calculator clues.The formula chart

What is the unknown?Home

Look at the last sentence of the question. Double underline the unknown.

See sample

The unknown usually follows after “what” or “how many” or “when” or “how far” etc.

Anything moving vertical

Push current Resistance

Velocity and speed are the same thing, except velocity should include the direction that the object is going. Sometimes on TAKS they use the word ‘velocity’ equally as ‘speed’.

See how to put formulas into a ‘triangle’

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A mechanic used a hydraulic lift to raise a

12,054 N car 1.89 m above the floor of a

garage. It took 4.75 s to raise the car. What

was the power output of the lift?

A 489 W

B 1815 W

C 4796 W

D 30,294 W

What are the other two units?Home

Sometimes there are clearly only two other numbers in the question.The units of those numbers tell you about the formula to look for on the formula chart.

Sample of units and their meaning on the formula chart.

Other times, only one number is given and an illustration gives the other number.

1. Sample of only one number given.

2. Sample of when only one number is given & you use the gravity number.

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Unit On the formula chart

kg or g

L or mLoC

km or m or cm

hour or sec

N

Mass

Volume

Temperature

Distance

Time

Force

Which wave has the greatest velocity?

Velocity = frequency times wavelength

1 x 2

2 x 8

3 x 3

4 x 1

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An ant crawled from Point A to Point B in4.0 seconds. To the nearest tenth, what was the ant’s speed in centimeters per second? Record and bubble in your answer on the answer document.

4cm ÷ 4 s = 1 cm/s

Back

How many newtons of force does a 50.0 kg

deer exert on the ground because of gravity? Record and bubble in your answer on the answer document.

490

Force = mass x acceleration of gravity50 kg x 9.8 =

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The ‘signs’ of the triangle.

Home ÷ ÷

x

How to use the triangle method

Home

÷ ÷

x

Cover the unknown with your finger. Do the function between the other two.

c

c = a ÷ b b = a ÷ ca= b x c

a

b

How to put formulas into the triangle.

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If part of the formula is already on top (numerator) it stays on the top.

If the formula doesn’t have a fraction, the ‘loner’ gets to be on top.

d

tsd

m

v

momentum

mass velocity

force

mass acceleration

work

force distance

Solving for an unknown using the “reverse the sign” method:

If distance is the unknown, x time

Speed x time = distance

x time

Speed = distance / time

Speed = distance / timeSpeed = distance / time

Another sample of “reverse the sign”

Solving for an unknown using the “reverse the sign” method:

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If time is the unknown,

Speed = distance / time

Speed = distance/time ÷ distance

Speed ÷ distance = time

Speed ÷ distance = distance/time ÷ distance

Solving for an unknown using the “cross multiply” method:

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If time is the unknown,

distance x 1 ÷ speed = time

Speed = distance 1 time

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Remember that ⅝ is pushed into the calculator as

5 ÷ 8 =

or

5 / 8 =