Important Trigonometry Formula for Class 11 Mathematics and Physics

Welcome student today we will going to mention the Important Trigonometry Formula  for Class 11 Mathematics, it's very important regarding mathematics and also for physics. 

Read it and learn it and then practice the MCQ of it Which link is below. 

´◔‿ゝ◔`)━☞ Trigonometric Identities:

(i) sin (x + y) = sinx cosy + cosx siny

(ii) sin (x – y) = sinx cosy – cosx siny

(iii) cos (x + y) = cosx cosy – sinx siny

(iv) cos (x – y) = cosx cosy + sinx siny 

(V) tan(A+B) = [(tan A + tan B)/(1 – tan A tan B)]

(vi) tan(A-B) = [(tan A – tan B)/(1 + tan A tan B)]

(vii) cot(A+B) = [(cot A cot B − 1)/(cot B + cot A)]

(viii) cot(A-B) = [(cot A cot B + 1)/(cot B – cot A)]

(ix) Sin2x = 2sinxcosx = 2tanx / 1 + tan²x 

(x) Cos2x = cos²x - sin²x = 1 - 2sin²x = 2cos²x - 1

                  = 1 - tan²x / 1 + tan²x

Trigonometry Important Formula 

• Cosx + Cosy = 2 Cos [x + y/2 ] Cos [ x - y / 2] 
• Cos x - Cos y = 2 Sin [ x - y / 2] Sin [ x - y / 2]
• Sin x + Sin y = 2 Sin [ x + y / 2] Cos [ x - y / 2]
• Sin x - Sin y = 2 Cos [ x + y / 2] Sin [ x - y / 2] 

Formulas for thrice of the angles:

• sin3A = 3sinA – 4sin3A
• cos3A = 4cos3A – 3cosA
• tan3A = [3tanA–tan3A]/[1−3tan2A]

Based on the above addition formulas for sin and cos, we get the following below formulas:

• sin(π/2-A) = cos A
• cos(π/2-A) = sin A
• sin(π-A) = sin A
• cos(π-A) = -cos A
• sin(π+A)=-sin A
• cos(π+A)=-cos A
• sin(2π-A) = -sin A
• cos(2π-A) = cos A 

Trigonometry Derive Identity 

•  2sinx cosy = sin(x + y) + sin(x – y)
•  2cosx siny = sin(x + y) – sin(x – y)
•  2cosx cosy = cos(x + y) + cos(x – y)
•  2sinx siny = cos(x – y) – cos(x + y)