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Trigonometric Formulas Class 11
Trigonometry formulas class 11 implement the concept of trigonometric ratios to trigonometric functions and their properties. These formulas are a considerably important part of higherlevel math studies. The application of class 11 trigonometry formulas is prevalent in engineering branches like civil engineering, mechanical, architecture, etc. Let us learn in detail about the practical applications and importance of class 11 trigonometric formulas.
List of Trigonometry Formulas Class 11
Here is a list of important Class 11 trigonometry formulas,

 Trigonometric Identities: sin² θ + cos² θ = 1
 cosec² θ – cot² θ = 1
 sec² θ – tan² θ = 1
 sin θ cosec θ = 1
 cos θ sec θ = 1
 tan θ cot θ = 1
 Sum and Difference Formulas: sin(x+y) = sin(x)cos(y) + cos(x)sin(y)
 cos(x+y) = cos(x)cos(y) – sin(x)sin(y)
 tan(x+y) = (tan x + tan y)/ (1−tan x • tan y)
 sin(x–y) = sin(x)cos(y) – cos(x)sin(y)
 cos(x–y) = cos(x)cos(y) + sin(x)sin(y)
 tan(x−y) = (tan x–tan y)/ (1+tan x • tan y)
Applications of Trigonometry Formulas Class 11
Trigonometry formulas Class 11 are widely applied in construction work, mechanical engineering, designing, seismology, oceanography, phonetics, architecture, etc. Many routine calculations in the various fields apply trigonometry formulas. Here are some uses of Class 11 trigonometry formulas:
 Trigonometry formulas are applied to evaluate the height of buildings, mountains, towers, angles of elevations and slopes.
 Another real life use of trigonometry formulas in calculating the distance between the ship and the seashore.
 These formulas help astronauts to determine the speed and altitude of celestial bodies.
 Representation of various physical quantities like oscillations, electromagnetic waves, mechanical waves, etc has a lot of application of trigonometric formulas.
 Trigonometry formulas are applied in solar cell panels to calculate the sun height angle to determine power output at different angles.
Tips to Memorize Trigonometry Formulas Class 11
Here are some useful tips to memorize trigonometry formulas class 11:
 Students should try to memorize all terms related to trigonometry formulas class 11. It will enable them to memorize better through conceptual understanding. Students should form an accurate understanding of each and every trigonometry concept to apply these formulas.
 Students should try to eliminate all their doubts and errors by referring to the interactive expertled study material online or by reaching out to their concerned teacher.
 Step by step deriving trigonometry formulas is also an excellent approach to enhance the foundational knowledge of all underlying concepts.
 After having crystal clear knowledge of the terms used in formulas students can try to use some fun tricks like phrases to remember them better.
 Students can download and set the trigonometry formulas images as wallpaper on their devices which will help them ensure a quick revision while they use their mobiles, tablets or laptops.
 Students should practice lots and lots of problems and examples given in the textbook. It will provide optimal coverage of the usage of formulas in different contexts.
Trigonometry Formula Class 11 Examples
Example: If A, B and C are interior angles of a triangle ABC, then show that
sin (B + C)/2 = cos A/2
Solution: In this question, we can use the trigonometric ratios of complementary angles to solve the given question.
sin (90°  θ) = cosθ
We know that the sum of angles of a ΔABC is 180°,
Therefore, ∠A + ∠B + ∠C = 180°
∠B + ∠C = 180°  ∠A
On dividing both sides by 2, we get,
(∠B + ∠C)/2 = (180°  ∠A)/2
(∠B + ∠C)/2 = 90°  ∠A/2
Applying sine angles on both the sides:
sin {(∠B + ∠C)/2} = sin (90°  ∠A/2)
Since, sin (90°  θ) = cos θ, we get
sin (∠B + ∠C)/2 = cos A/2.
Students can download the printable Maths Formulas Class 11 sheet from below.
FAQs On Trigonometry Formulas Class 11
What are the Important Trigonometry Formulas Class 11?
The important trigonometry formulas Class 11 are as below:
 sin (x + y) = sin x cos y + cos x sin y
 sin (x  y) = sin x cos y – cos x sin y
 cos (x + y) = cos x cos y – sin x sin y
 cos (x – y) = cos x cos y + sin x sin y
What are the RealLife Applications of Trigonometry Formulas Class 11?
Trigonometry formulas Class 11 are often applied in industrial calculations like designing, seismology, oceanography, phonetics, architecture, etc. Many routine calculations like measuring the height of buildings, mountains, towers, angles of elevations and slopes see the use of trigonometry formulas.
Why should you Practice Questions Based on Trigonometry Formulas for Class 11?
Solving questions based on trigonometry formulas for Class 11 will enable students to understand the use of trigonometric formulas in various contexts. It will also help them prepare effectively for various competitive exams and academic tests. Students will be able to build problemsolving skills and form a core conceptual understanding of this topic by practicing practical problems based on it.
How to Memorize Trigonometry Formulas Class 11?
Memorizing trigonometry formulas Class 11 requires practice and perseverance. With the practice of a wide range of questions based on this formula, students will gain deep knowledge of the core concepts. They will also learn some creative ways to memorize formulas and important theorems. It will enable them to employ their knowledge of formulas in various situations, which is highly useful for facing competitive exams.
How Many Formulas are there in Trigonometry Class 11 Maths?
There are around 20 main formulas present in trigonometry Class 11 maths. Students are advised to thoroughly go through each and every formula provided in the list to have a clear idea of the terms and concepts applied in this topic. This is also helpful in solving various types of problems covered under this topic.
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