If sinA+cosA=
3
4
, then find the value of tanA+cotA.
- A7
18
- B4
3
- C18
7
- D3
4
Solution & Step-by-step Explanation
Given:
sinA+cosA=
3
4
Squaring both sides:
(sinA+cosA)
2
=(
3
4
)
2
sin
2
A+cos
2
A+2sinAcosA=
9
16
Since sin
2
A+cos
2
A=1:
1+2sinAcosA=
9
16
2sinAcosA=
9
16
−1=
9
7
sinAcosA=
18
7
Now, let's simplify the expression we need to find:
tanA+cotA=
cosA
sinA
+
sinA
cosA
=
sinAcosA
sin
2
A+cos
2
A
=
sinAcosA
1
Substitute the value of sinAcosA:
tanA+cotA=
18
7
1
=
7
18
sinA+cosA=
3
4
Squaring both sides:
(sinA+cosA)
2
=(
3
4
)
2
sin
2
A+cos
2
A+2sinAcosA=
9
16
Since sin
2
A+cos
2
A=1:
1+2sinAcosA=
9
16
2sinAcosA=
9
16
−1=
9
7
sinAcosA=
18
7
Now, let's simplify the expression we need to find:
tanA+cotA=
cosA
sinA
+
sinA
cosA
=
sinAcosA
sin
2
A+cos
2
A
=
sinAcosA
1
Substitute the value of sinAcosA:
tanA+cotA=
18
7
1
=
7
18