Show that semi-vertical angle of a cone of maximum volume and gi

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 Multiple Choice QuestionsShort Answer Type

401.

Find the equation of tangents to the curve y= x3+2x-4, which are perpendicular to line x+14y+3 =0.

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 Multiple Choice QuestionsLong Answer Type

402. Prove space that space straight y equals fraction numerator 4 space sin space straight theta over denominator 2 space plus cos space straight theta end fraction space minus straight theta space is space an space increasing space function space of space straight theta space on space open square brackets 0 comma straight pi over 2 close square brackets
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403.

Show that semi-vertical angle of a cone of maximum volume and given slant height is cos-1fraction numerator 1 over denominator square root of 3 end fraction.


Volume space of space cone space equals 1 third πr squared straight h
space equals 1 third straight pi left parenthesis space straight l space sin space straight alpha right parenthesis squared space left parenthesis space straight l space space cos space straight alpha right parenthesis
equals 1 third space straight pi space straight l cubed space sin squared space straight alpha space cos space straight alpha
dv over dα equals πl cubed over 3 left square bracket negative sin cubed space straight alpha space plus 2 sin space straight alpha space cosx space. cos space straight alpha right square bracket
equals fraction numerator straight pi space straight l cubed space sin space straight alpha over denominator 3 end fraction left parenthesis negative sin squared space straight alpha space plus space 2 space cos squared space straight alpha right parenthesis
For space maximum space volume


dv over dα space equals 0
fraction numerator πl cubed space sin space straight alpha over denominator 3 end fraction left parenthesis negative s i n space squared space alpha space plus 2 space c o s squared space alpha right parenthesis equals 0
s i n space alpha space not equal to 0
space 2 space c o s squared space alpha space equals space s i n squared space alpha
t a n squared space alpha space equals 2
t a n alpha space equals square root of 2
c o s space alpha space equals space fraction numerator 1 over denominator square root of 3 end fraction
alpha space equals space c o s to the power of negative 1 end exponent fraction numerator 1 over denominator square root of 3 end fraction

again space diff space straight w. straight r. straight t space straight alpha comma space we space get
fraction numerator straight d squared straight v over denominator dα squared end fraction space equals 1 third πl cubed cos squared space straight alpha left parenthesis 2 minus 7 space tan squared space straight alpha right parenthesis
at space cos space straight alpha space equals fraction numerator 1 over denominator square root of 3 end fraction
fraction numerator straight d squared straight v over denominator dα squared end fraction space less than 0
straight V space is space maximum space when space cos space straight alpha space equals fraction numerator 1 over denominator square root of 3 end fraction space or space straight alpha space equals cos to the power of negative 1 end exponent fraction numerator 1 over denominator square root of 3 end fraction
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404.

Find the absolute maximum and absolute minimum values of the function f given by
straight f left parenthesis straight x right parenthesis space equals sin squared straight x minus cosx comma space straight x space element of space left parenthesis 0 comma space straight pi right parenthesis

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 Multiple Choice QuestionsShort Answer Type

405.

Find the value(s) of x for which y = open square brackets straight x left parenthesis straight x minus 2 right parenthesis close square brackets squared is an increasing function.

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406.

Find the equations of the tangent and normal to the curve straight x squared over straight a squared minus straight y squared over straight b squared equals 1 space at space the space point space open parentheses square root of 2 straight a comma space straight b close parentheses.

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 Multiple Choice QuestionsLong Answer Type

407.

If the sum of the lengths of the hypotenuse and a side of a right triangle is given, show that the area of the triangle is maximum when the angle between them is 60 degree.

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408.

Show that the height of the cylinder of maximum volume, which can be inscribed in a sphere of radius R is  Also find the maximum volume. 

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409.

Find the equation of the normal at a point on the curve x2 = 4y which passes through the point (1, 2). Also, find the equation of the corresponding tangent.

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 Multiple Choice QuestionsShort Answer Type

410.

The volume of a sphere is increasing at the rate of 3 cubic centimetres per second. Find the rate of increase of its surface area, when the radius is 2 cm.

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