Find the minimum and maximum value of $3\sin x + 4\cos x + 5$.
Find the minimum and maximum value of $3\sin x + 4\cos x + 5$.
1 Answer
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· 2mo ago
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The expression $a\sin x + b\cos x$ always lies within the range $[-\sqrt{a^2 + b^2}, \sqrt{a^2 + b^2}]$.
Here, $a = 3$ and $b = 4$.
$$\sqrt{3^2 + 4^2} = \sqrt{9 + 16} = 5$$
So, $-5 \le 3\sin x + 4\cos x \le 5$.
Now add 5 across the inequality:
$$-5 + 5 \le 3\sin x + 4\cos x + 5 \le 5 + 5$$
$$0 \le 3\sin x + 4\cos x + 5 \le 10$$
Minimum value = 0, Maximum value = 10.
Answer: Min = 0, Max = 10
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Discussion (3)
S
Adding for context: NCERT covers the base concept in the same chapter.
N
Brilliant explanation, the substitution step is what I kept missing.
VA
Great discussion here. If you want more practice on this concept, check the related questions in this category.