This question is from trigonometry
topic – trigonometric ratios on complementary angles
We have been asked to prove that sin35°sin55° – cos35°cos55° = 0 without using trigonometric tables
RS Aggarwal, class 10, chapter 12, question no 3(iv)
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We know that, sin (90 – θ) = cos θ So, the given can be expressed as sin (90 – 55)° sin (90 – 35)° – cos 35° cos 55°
= cos 55° cos 35° – cos 35° cos 55°
= 0