যদি sin23°=p হয় তবে sin67° এর মান p এর আকারে লেখো

প্রশ্ন

যদি sin23°=p হয় তবে sin67° এর মান p এর আকারে লেখো

উত্তর

\sqrt{1-p^2}

ব্যাখ্যা / সমাধান

Method 1

প্রদত্ত:

\sin23^\circ=p

এখন: \sin67^\circ

= \cos(90^\circ - 67^\circ) \; \; [cos(90^\circ - \theta) = \sin\theta]

= \cos23^\circ

= \sqrt{1 - (\sin23^\circ)^2} \; \; [\because \cos\theta = \sqrt{1 - sin^2\theta}]

= \sqrt{1 - (p)^2}

= \sqrt{1-p^2} \; \text(Answer)

Alternative method:

\sin67^\circ

= \sin(90^\circ - 23^\circ)

= \sin90^\circ\cos23^\circ - \cos90^\circ\sin23^\circ \; \; [\sin\text{(A-B)} = \sin\text{A} \cos\text{B} - \cos\text{A} \sin\text{B}]

= \sin90^\circ\cos23^\circ [\because \cos90^\circ = 0 \Rightarrow \cos90^\circ\sin23^\circ = 0]

= \cos23^\circ \; \; [\because \sin90^\circ= 1]

= \sqrt{1 - (\sin23^\circ})^2 \; \; [\cos\theta= \sqrt{1- \sin^2\theta}]

= \sqrt{1 - (p)^2}

= \sqrt{1 -p^2} \; \text(Answer)

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