trigonometric identity exercise 21A q-28 to 33 icse Selina mathematics

I.C.S.E.

28. (cot^2 A)/((co * sec(A) + 1) ^ 2) = (1 - sin A)/(1 + sin A)

29. (1 + sin A)/(cos A) + (cos A deg)/(1 + sin A) = 2sec(A)

P = 2l + 2w

trigonometric identity exercises 21A

30. (1 - sin A)/(1 + sin A) = (sec(A) - tan A) ^ 2

31. ( cot A-cosec A)^ 2 = (1 - cos A)/(1 + cos A)

32. (co * sec(A) - 1)/(co * sec(A) + 1) = ((cos A)/(1 + sin A)) ^ 2

33. tan^2 A - tan^2 B = sin^ 2 A-sin^ 2 B cos^ 2 A.cos^ 2 B

Here’s a YouTube description for the problems you listed:

Title: Trigonometric Identities | ICSE Class 10 | Exercise 21A

Description:
In this video, we dive into solving challenging trigonometric identity problems from ICSE Class 10, Exercise 21A. These problems require a solid understanding of trigonometric formulas and identities. We will break down each step to simplify these expressions and reach the required results.

Problems Covered:

Simplify:
cot
⁡
2
A
(
cosec
⁡
A
+
1
)
2
=
1
−
sin
⁡
A
1
+
sin
⁡
A
(cosecA+1)
2

cot
2
A

=
1+sinA
1−sinA



Prove:
1
+
sin
⁡
A
cos
⁡
A
+
cos
⁡
A
1
+
sin
⁡
A
=
2
sec
⁡
A
cosA
1+sinA

+
1+sinA
cosA

=2secA

Solve using trigonometric identities:
1
−
sin
⁡
A
1
+
sin
⁡
A
=
(
sec
⁡
A
−
tan
⁡
A
)
2
1+sinA
1−sinA

=(secA−tanA)
2


Simplify:
(
cot
⁡
A
−
cosec
⁡
A
)
2
=
1
−
cos
⁡
A
1
+
cos
⁡
A
(cotA−cosecA)
2
=
1+cosA
1−cosA



Prove:
cosec
⁡
A
−
1
cosec
⁡
A
+
1
=
(
cos
⁡
A
1
+
sin
⁡
A
)
2
cosecA+1
cosecA−1

=(
1+sinA
cosA

)
2


Simplify:
tan
⁡
2
A
−
tan
⁡
2
B
=
sin
⁡
2
A
−
sin
⁡
2
B
cos
⁡
2
A
cos
⁡
2
B
tan
2
A−tan
2
B=
cos
2
Acos
2
B
sin
2
A−sin
2
B



Stay tuned to master these identities and strengthen your understanding of trigonometry! 🚀

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