D
5
B
С
21
X
From the figure (1) given below, find the values of:
(1)
(1) 2 sin y -cos y
iii) 1 - sin x + cos y
in the figure (2) given below, AABC is right-angled a
3C = 3 units and CA = 5 units, find
(ii) y.
(ii) 2 sin x - COS
(iv) 2 cos X - 3 sir
1) sin xº
В.
Answers
Answer:
Let a be the side of the equilateral triangle ABC.
∴ AB=BC=AC=a
and since ΔABC is an equilateral triangle
∠A=∠B=∠C=60
o
Given, radius of the circumcircle, r=6cm
Since the triangle ABC is equilateral, its perpendicular bisector i.e. the median meet at the same point O which is the centre of the in circle
∴ AD is the perpendicular bisector of BC.
⇒ BD=DC=
2
1
BC
=
2
a
and OB is the angle bisector of ∠B.
∴∠ABO =∠ OBD =
2
60
o
=30
o
In rt Δ ODB
sin30
o
=
OB
OD
⇒
2
1
=
r
OD
⇒OD=
2
r
⇒OD=
2
6
⇒OD=3cm
∴ Radius of the incircle =3cm.
solution
Step-by-step explanation:
Let a be the side of the equilateral triangle ABC.
∴ AB=BC=AC=a
and since ΔABC is an equilateral triangle
∠A=∠B=∠C=60
o
Given, radius of the circumcircle, r=6cm
Since the triangle ABC is equilateral, its perpendicular bisector i.e. the median meet at the same point O which is the centre of the in circle
∴ AD is the perpendicular bisector of BC.
⇒ BD=DC=
2
1
BC
=
2
a
and OB is the angle bisector of ∠B.
∴∠ABO =∠ OBD =
2
60
o
=30
o
In rt Δ ODB
sin30
o
=
OB
OD
⇒
2
1
=
r
OD
⇒OD=
2
r
⇒OD=
2
6
⇒OD=3cm
∴ Radius of the incircle =3cm.
solution