Math, asked by kr2835733, 6 months ago

प्रश्न.8. cos(-1080°) का मान ज्ञात कीजिए​

Answers

Answered by MaheswariS
1

\underline{\textsf{To find:}}

\textsf{The value of}

\mathsf{cos(-1080^{\circ})}

\underline{\textsf{Solution:}}

\mathsf{Consider,}

\mathsf{cos(-1080^{\circ})}

\mathsf{Using,\;\boxed{\bf\;cos(-A)=cosA}}

\mathsf{=cos1080^{\circ}}

\mathsf{=cos(3(360^{\circ})+0^\circ)}

\mathsf{=cos0^\circ}

\mathsf{(\because\;\;0^\circ\;and\;1080^\circ\;are\;co-terminus\;angles)}

\mathsf{=1}

\implies\boxed{\boxed{\bf\mathsf{cos(-1080^{\circ})=1}}}

\underline{\textsf{Find more:}}

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Answered by pulakmath007
19

समाधान

निर्धारित करना है

cos(-1080°) का मान

समाधान

Step : 1

Write down the given expression cos(-1080°)

Step : 2

Cos is an even function

∴ cos(-1080°) = cos 1080°

Step : 3

Express 1080° in terms of 90°

1080° = ( 12 × 90° ) + 0°

Step : 4

The angle 1080° lies in Fourth Quadrant

Step : 5

 \sf{ \cos( -  {1080}^{ \circ}) }

 =  \sf{ \cos {1080}^{ \circ} }

 =  \sf{ \cos( 12 \times   {90}^{ \circ} + {0}^{ \circ}) }

 =  \sf{ \cos {0}^{ \circ} }

 = 1

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