21. 15. Which of the following is true for all values of π(00 β€
π
β€
900) ?
(a)Cos2 π-sin2 π=1
(b)Cosec2 π-sec2 π=1
(c) Sec2 π β tan2 π=1
(d)Cot2 π tan2 π=1
22. 16. If tan A =
15
12
, find the value of (sin A + cos A) sec A.
23. 17. If tan A =
15
12
, find the value of (sin A + cos A) sec A.
24. 18. If 3x = cosec π and
3
π₯
= cot π, find the value of 3 π₯2 β
1
π₯2 .
25. 19. If tan(A+B)= 3 and tan(A-B) =
1
3
,A>B, then the value of A is _____.
26. 20. If 5tan π=3, then what is the value of
5 π πππβ3πππ π
4 π πππ + 3 cos π
?
27. 21. The value of π ππ2π +
1
1+π‘ππ2π
= _________.
28. 22. The value of (1 + tan2 π) (1-sin π) (1+sin π)= ____________.
29. 23. In a βπ΄π΅πΆ, right-angled at C, if tanA =
1
3
, find the value of sinA CosB + cosA sinB.
30.
31. 24. If cot π=
15
8
, then evaluate
(2+2π πππ)(1βπ πππ)
(1+πππ π)(2β2πππ π)
.
37. 27. The rod AC of a TV disc antenna is fixed at right angles to the wall, AB and a rod CD is
Supporting the disc as shown in Fig.4. if AC= 1.5m long and CD =3 m,
find (i) tanπ (ii) secπ + cosecπ.
41. 29. Evaluate: A)
5
πππ‘2300 +
1
π ππ260o β πππ‘2450 + 2π ππ2900
(B) if ΞΈ is an acute angle and sinπ = cosπ, find the value of tan2π+ cot2 - 2.
42.
43. 30. Prove that: (1+cot A + tan A)(sin A β cos A)= sin A tan A β cot A cos A.
44.
45. 31. Prove the following:
(cosec A-Sin A)(Sec A-cos A) =
1
tan π΄+cot π΄
46.
47. 32. If 4 tanΞΈ = 3, evaluate
4 sin ΞΈβcos ΞΈ+1
4 sin ΞΈ+cos ΞΈβ1