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earnstyle [38]
3 years ago
9

Solve without using a calculator: sin²20° + sec²20°

Mathematics
1 answer:
PolarNik [594]3 years ago
7 0

Step-by-step explanation:

sin

2

(

20

°

)

+

sec

2

(

20

°

)

Simplify each term.

Tap for fewer steps...

Rewrite

sec

(

20

°

)

in terms of sines and cosines.

sin

2

(

20

°

)

+

(

1

cos

(

20

°

)

)

2

Apply the product rule to

1

cos

(

20

°

)

.

sin

2

(

20

°

)

+

1

2

cos

2

(

20

°

)

One to any power is one.

sin

2

(

20

°

)

+

1

cos

2

(

20

°

)

Simplify each term.

Tap for fewer steps...

Rewrite

1

as

1

2

.

sin

2

(

20

°

)

+

1

2

cos

2

(

20

°

)

Rewrite

1

2

cos

2

(

20

°

)

as

(

1

cos

(

20

°

)

)

2

.

sin

2

(

20

°

)

+

(

1

cos

(

20

°

)

)

2

Convert from

1

cos

(

20

°

)

to

sec

(

20

°

)

.

sin

2

(

20

°

)

+

sec

2

(

20

°

)

The result can be shown in multiple forms.

Exact Form:

sin

2

(

20

°

)

+

sec

2

(

20

°

)

Decimal Form:

1.24945210

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Rewrite each of these statements so that negations appear only within predicates (that is, so that no negation is outside a quan
Ghella [55]

Answer:

Follows are the solution to the given point:

Step-by-step explanation:

In point a:

¬∃y∃xP (x, y)  

∀x∀y(>P(x,y))  

In point b:

¬∀x∃yP (x, y)

 ∃x∀y  ¬P(x,y)

In point c:

¬∃y(Q(y) ∧ ∀x¬R(x, y)) \equiv  ∀y(> Q(y) V ∀ ¬ (¬R(x,y)))

∀y(¬Q(Y)) V ∃xR(x,y) )

In point d:

¬∃y(∃xR(x, y) ∨ ∀xS(x, y))  

∀y(∀x>R(x,y)) \wedge ∃x>s(x,y))

In point e:

¬∃y(∀x∃zT (x, y, z) ∨ ∃x∀zU (x, y, z))

∀y(∃x ∀z)>T(x,y,z) \wedge ∀x ∃z> V (x,y,z))  

8 0
3 years ago
In Exercises 40-43, for what value(s) of k, if any, will the systems have (a) no solution, (b) a unique solution, and (c) infini
svet-max [94.6K]

Answer:

If k = −1 then the system has no solutions.

If k = 2 then the system has infinitely many solutions.

The system cannot have unique solution.

Step-by-step explanation:

We have the following system of equations

x - 2y +3z = 2\\x + y + z = k\\2x - y + 4z = k^2

The augmented matrix is

\left[\begin{array}{cccc}1&-2&3&2\\1&1&1&k\\2&-1&4&k^2\end{array}\right]

The reduction of this matrix to row-echelon form is outlined below.

R_2\rightarrow R_2-R_1

\left[\begin{array}{cccc}1&-2&3&2\\0&3&-2&k-2\\2&-1&4&k^2\end{array}\right]

R_3\rightarrow R_3-2R_1

\left[\begin{array}{cccc}1&-2&3&2\\0&3&-2&k-2\\0&3&-2&k^2-4\end{array}\right]

R_3\rightarrow R_3-R_2

\left[\begin{array}{cccc}1&-2&3&2\\0&3&-2&k-2\\0&0&0&k^2-k-2\end{array}\right]

The last row determines, if there are solutions or not. To be consistent, we must have k such that

k^2-k-2=0

\left(k+1\right)\left(k-2\right)=0\\k=-1,\:k=2

Case k = −1:

\left[\begin{array}{ccc|c}1&-2&3&2\\0&3&-2&-1-2\\0&0&0&(-1)^2-(-1)-2\end{array}\right] \rightarrow \left[\begin{array}{ccc|c}1&-2&3&2\\0&3&-2&-3\\0&0&0&-2\end{array}\right]

If k = −1 then the last equation becomes 0 = −2 which is impossible.Therefore, the system has no solutions.

Case k = 2:

\left[\begin{array}{ccc|c}1&-2&3&2\\0&3&-2&2-2\\0&0&0&(2)^2-(2)-2\end{array}\right] \rightarrow \left[\begin{array}{ccc|c}1&-2&3&2\\0&3&-2&0\\0&0&0&0\end{array}\right]

This gives the infinite many solution.

5 0
3 years ago
In ΔFGH, what is the measure of < H?
kogti [31]
X + x - 1 + 43 = 180.  Solve for x.  2x +42 = 180 and 2x = 138.  Therefore, x = 69.  If x = 69, then angle H is 68 and angle G is 69.  68 + 69 + 43 = 180.

3 0
3 years ago
For the following right triangle, find the side length of x. round your answer to the nearest hundredth.
tatyana61 [14]

Answer:

14.87 units

Step-by-step explanation:

The sides of all right triangles share the same relationship known as the Pythagorean Theorem a² + b² = c². Substitute the lengths of the triangle into the theorem and solve for the unknown side. Since the problem does have an attached a picture, assume that a = 10, b = 11, and c = x.

10² + 11² = x²

100 + 121 = 221²

221 = x²

√221 = √x²

14.87 = x

6 0
3 years ago
True or False<br> 3 is a factor of n(n + 2)(n − 1) by mathematical induction.<br> Explain why.
Crazy boy [7]

Answer:

false

Step-by-step explanation:

this beacuse when is times with the base that shows the product thats the factor

8 0
2 years ago
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