Q3 of 90 Page 7

Show that Sin 1000 – Sin 100 is positive.

Let f(x) = sin 100° – sin 10°


Dividing And multiplyingBy √(1 + 1) = √2,





We know that cosA cosB – sinA sinB = cos(A +B)



∴ f(x) = √2 cos 55°


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