// Numbas version: finer_feedback_settings {"name": "Exact values for sin, cos, tan (0 to 330, degrees)", "extensions": ["geogebra"], "custom_part_types": [], "resources": [["question-resources/exact_values.svg", "exact_values_HBd4LtO.svg"], ["question-resources/ASTCwhite.png", "ASTCwhite_0FVod00.png"]], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Exact values for sin, cos, tan (0 to 330, degrees)", "tags": ["trig", "trigonometry", "Trigonometry"], "metadata": {"description": "

exact value of sin, cos, tan of  random(0,90,120,135,150,180,210,225,240,270,300,315,330) degrees

", "licence": "Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International"}, "statement": "

Often we prefer to work with exact values rather than approximations from a calculator. In this question we require you input your answer without decimals and without entering the words sin, cos or tan. For example to input the exact value of $\\sin(60^\\circ)$, which is $\\dfrac{\\sqrt{3}}{2}$, you would input sqrt(3)/2

", "advice": "

Recall the unit circle definitions:

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In particular, the angle of $\\var{theta}^\\circ$ puts the point {textquadrant}.

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{diagram}

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Since this point falls on an axis and the point is on the unit circle, it is clear that its coordinates are $(\\var{cos({theta}*pi/180)}, \\var{sin({theta}*pi/180)})$. From these, we can conclude that 

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$\\sin(\\var{theta}^\\circ)=\\var{sin({theta}*pi/180)}$,

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$\\cos(\\var{theta}^\\circ)=\\var{cos({theta}*pi/180)}$, and

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$\\tan(\\var{theta}^\\circ)=\\dfrac{\\sin(\\var{theta}^\\circ)}{\\cos(\\var{theta}^\\circ)}=\\dfrac{\\var{sin({theta}*pi/180)}}{\\var{cos({theta}*pi/180)}}\\var{if(theta=90 or theta=270, \" which is undefined\",\" = \" + precround(tan(theta*pi/180),0))}.$

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The triangle {textquadrant} has the same side lengths as the related triangle in the first quadrant (they are congruent). Therefore, we can recall or use right-angled triangle trigonometry to determine the lengths of the triangle in the first quadrant and then change the signs as needed. Recall: 

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By drawing the following triangles, we can determine the exact values of $\\sin$, $\\cos$ and $\\tan$ for the angles $30^\\circ$, $45^\\circ$ and $60^\\circ$.

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Alternatively, one can memorise the following table: 

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
$30^\\circ$$45^\\circ$$60^\\circ$
 
$\\sin$$\\dfrac{1}{2}$$\\dfrac{1}{\\sqrt{2}}$$\\dfrac{\\sqrt{3}}{2}$
 
$\\cos$$\\dfrac{\\sqrt{3}}{2}$$\\dfrac{1}{\\sqrt{2}}$$\\dfrac{1}{2}$
 
$\\tan$$\\dfrac{1}{\\sqrt{3}}$$1$$\\sqrt{3}$
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From the above, the triangle in the first quadrant tells us that:

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$\\sin(\\var{phi}^\\circ)=\\;\\;\\dfrac{1}{2}$$\\sin(\\var{phi}^\\circ)=\\dfrac{1}{\\sqrt{2}}$$\\sin(\\var{phi}^\\circ)=\\dfrac{\\sqrt{3}}{2}$

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$\\cos(\\var{phi}^\\circ)=\\dfrac{\\sqrt{3}}{2}$$\\cos(\\var{phi}^\\circ)=\\dfrac{1}{\\sqrt{2}}$$\\cos(\\var{phi}^\\circ)=\\;\\;\\dfrac{1}{2}$

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$\\tan(\\var{phi}^\\circ)=\\dfrac{1}{\\sqrt{3}}$$\\tan(\\var{phi}^\\circ)=\\;\\;1$$\\tan(\\var{phi}^\\circ)=\\sqrt{3}$

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Since $\\theta=\\var{theta}^\\circ$ puts us {textquadrant}, the $x$-coordinate (the cosine value) is positive,negative, and the $y$-coordinate (the sine value) is positivenegative. That is:

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$\\sin(\\var{theta}^\\circ)=\\phantom{-}\\sin(\\var{phi}^\\circ)=\\;\\;\\phantom{-}\\dfrac{1}{2}$$\\sin(\\var{theta}^\\circ)=\\phantom{-}\\sin(\\var{phi}^\\circ)=\\phantom{-}\\dfrac{1}{\\sqrt{2}}$$\\sin(\\var{theta}^\\circ)=\\phantom{-}\\sin(\\var{phi}^\\circ)=\\phantom{-}\\dfrac{\\sqrt{3}}{2}$

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$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=-\\dfrac{\\sqrt{3}}{2}$$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{2}}$$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=\\;\\;-\\dfrac{1}{2}$

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$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{3}}$$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=\\;\\;-1$$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=-\\sqrt{3}$

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$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=\\;\\;-\\dfrac{1}{2}$$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{2}}$$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=-\\dfrac{\\sqrt{3}}{2}$

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$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=-\\dfrac{\\sqrt{3}}{2}$$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{2}}$$\\cos(\\var{theta}^\\circ)=-\\cos(\\var{phi}^\\circ)=\\;\\;-\\dfrac{1}{2}$

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$\\tan(\\var{theta}^\\circ)=\\phantom{-}\\tan(\\var{phi}^\\circ)=\\phantom{-}\\dfrac{1}{\\sqrt{3}}$$\\tan(\\var{theta}^\\circ)=\\phantom{-}\\tan(\\var{phi}^\\circ)=\\phantom{-}\\;\\;1$$\\tan(\\var{theta}^\\circ)=\\phantom{-}\\tan(\\var{phi}^\\circ)=\\phantom{-}\\sqrt{3}$

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$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=\\;\\;-\\dfrac{1}{2}$$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{2}}$$\\sin(\\var{theta}^\\circ)=-\\sin(\\var{phi}^\\circ)=-\\dfrac{\\sqrt{3}}{2}$

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$\\cos(\\var{theta}^\\circ)=\\phantom{-}\\cos(\\var{phi}^\\circ)=\\phantom{-}\\dfrac{\\sqrt{3}}{2}$$\\cos(\\var{theta}^\\circ)=\\phantom{-}\\cos(\\var{phi}^\\circ)=\\phantom{-}\\dfrac{1}{\\sqrt{2}}$$\\cos(\\var{theta}^\\circ)=\\phantom{-}\\cos(\\var{phi}^\\circ)=\\;\\;\\phantom{-}\\dfrac{1}{2}$

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$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=-\\dfrac{1}{\\sqrt{3}}$$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=\\;\\;-1$$\\tan(\\var{theta}^\\circ)=-\\tan(\\var{phi}^\\circ)=-\\sqrt{3}$

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An alternative approach is to use the mnemonic \"All Stations TCentral\" or \"ASTC\" to recall which trig functions are positive in each quadrant (and hence which are negative):

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", "rulesets": {}, "extensions": ["geogebra"], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"theta": {"name": "theta", "group": "Ungrouped variables", "definition": "random(0,90,120,135,150,180,210,225,240,270,300,315,330)", "description": "", "templateType": "anything", "can_override": false}, "quadrant": {"name": "quadrant", "group": "Ungrouped variables", "definition": "switch(90The exact value of $\\sin(\\var{theta}^\\circ)$ is [[0]].

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The exact value of $\\cos(\\var{theta}^\\circ)$ is [[1]].

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If $\\tan(\\var{theta}^\\circ)$ is defined, what is its exact value? Otherwise, enter undefined  [[2]].

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