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Pythagoras’ theorem states that for any right-angled triangle c2 = b2 + a2. These are labelled on the triangle below. c is the longest side of the triangle, or hypotenuse.
We can use this relationship between side lengths to work out missing values, for example in biomechanics we can calculate resultant take-off velocity for a given horizontal and vertical velocity at take-off, if we assume the hypotenuse is our resultant velocity.
If b={b}m, and a = {a}m, what is the length of the hypotenuse?
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", "minValue": "sqrt({c_2}^2-{a_2}^2)", "maxValue": "sqrt({c_2}^2-{a_2}^2)", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": "2", "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"type": "numberentry", "useCustomName": false, "customName": "", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "If b={b_3}m, and c = {c_3}m, what is the length of a?
", "minValue": "sqrt({c_3}^2-{b_3}^2)", "maxValue": "sqrt({c_3}^2-{b_3}^2)", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"type": "information", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "Now consider that the sides of the triangle each represent a velocity. Side ‘a’ represents the amount of vertical velocity an object has, side ‘b’ is the horizontal velocity, and the hypotenuse, side ‘c’, is the resultant velocity.
Let’s say we kick a football. We impart both horizontal and vertical velocity components to it, which contribute to resultant velocity. Imagine that the horizontal velocity we impart is 3 m/s, and the vertical is 2 m/s. What is the resultant velocity (V) of the ball?
First we draw it out as a triangle:
\n
Becomes
\nUse Pythagoras to write out the problem and calculate ‘V’:
V2 = 22 + 32
V2 = 4 + 9 = 13
V= √13
V=3.6 m/s
A footballer runs at {a_4} m/s and then jumps to avoid a tackle. The vertical velocity of the jump was {b_4} m/s, what was the resultant velocity at the time of the jump?
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