Trigonometric Functions — Revision Notes
CBSE · Class 11 · Mathematics
Trigonometric Functions revision notes for CBSE Class 11 Mathematics: 4 topics in quick points. Part of the CBSE Class 11 Mathematics syllabus.
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Key Topics to Revise
1. Angle Measure and Radian Measure
- Angle is a measure of rotation of a given ray about its initial point.
- Anticlockwise rotation gives a positive angle and clockwise rotation gives a negative angle.
- One degree is one three-hundred-sixtieth part of a revolution.
2. Unit Circle Definition and Basic Values
- For a point P(a, b) on the unit circle, cos x = a and sin x = b.
- For every point on the unit circle, cos²x + sin²x = 1.
- At quadrantal angles, the points on the unit circle are A(1, 0), B(0, 1), C(-1, 0), and D(0, -1).
3. Other Trigonometric Functions, Domains, Ranges, and Signs
- cosec x = 1/sin x, sec x = 1/cos x, tan x = sin x/cos x, cot x = cos x/sin x.
- sin x = 0 implies x = nπ, where n is any integer.
- cos x = 0 implies x = (2n + 1)π/2, where n is any integer.
4. Trigonometric Identities and Formulas
- cos(x + y) = cos x cos y − sin x sin y.
- sin(x + y) = sin x cos y + cos x sin y.
- tan(x + y) = (tan x + tan y)/(1 − tan x tan y), provided none of x, y, or x + y is an odd multiple of π/2.
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Sources & Official References
- NCERT Official — ncert.nic.in
- CBSE Academic — cbseacademic.nic.in
- CBSE Official — cbse.gov.in
- National Education Policy 2020 — education.gov.in
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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