Question

Find the max. and min. value of

y = 7cosA + 24sinA

Joshi sir comment

   7cosA + 24sinA

= 25[7cosA/25 + 24sinA/25] = 25[cosAcosB + sinAsinB]                          where tanB = 24/7

= 25cos[A-B]                    max and min of cos[A-B] = 1 and -1                

so max. = 25  and min. = -25

Read 3 Solution.

when A= zero degree it will be min as sin=0 and cos=1 thus value is y=7 but if negative value is allowed so use A=180 y=-7  now max when A=90  cos =0 sin=1 max value=24 of y

SARIKA SHARMA 7 year ago is this solution helpfull: 4 3

for min 180 deg

for max 90 deg

SARIKA SHARMA 7 year ago is this solution helpfull: 5 2

Use the property,

The Maximum and Minimum value of asinx +bcosx is Root(a+ b2)   and   - root(a2 + b2)

 

HEMANT DESAI 6 year ago is this solution helpfull: 2 1

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