Prove the identities sinx + cosx = 1 – 3 sinx cosx

Asked by Aaryan | 1 year ago |  70

1 Answer

Solution :-

Let us consider LHS: sinx + cosx

(sinx) 3 + (cosx) 3

By using the formula, a3 + b3 = (a + b) (a2 + b2 – ab)

(sinx + cosx) [(sinx) 2 + (cosx) 2 – sinx cosx]

By using the formula, sinx + cosx = 1 and a2 + b2 = (a + b) 2 – 2ab

1 × [(sinx + cosx) 2 – 2sinx cosx – sinx cosx

12 – 3sinx cosx

1 – 3sinx cosx

= RHS

∴ LHS = RHS

Hence proved.

Answered by Sakshi | 1 year ago

Related Questions

prove that \(sin \dfrac{8π}{3} cos \dfrac{23π}{6} + cos \dfrac{13π}{3} sin \dfrac{35π}{6} = \dfrac{1}{2}\)

Class 11 Maths Trigonometric Functions View Answer

prove that \( 3 sin \dfrac{π}{6} sec \dfrac{π}{3} – 4 sin \dfrac{5π}{6} cot \dfrac{π}{4} = 1\)

Class 11 Maths Trigonometric Functions View Answer

prove that \( tan \dfrac{11π}{3} – 2 sin \dfrac{4π}{6} – \dfrac{3}{4} cosec^2 \dfrac{π}{4} + 4 cos^2 \dfrac{17π}{6} = \dfrac{(3 – 4\sqrt{3})}{2}\)

Class 11 Maths Trigonometric Functions View Answer