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pav-90 [236]
3 years ago
7

CosA.cos2A.cos4A=sin8A/8sinA​

Mathematics
1 answer:
alexgriva [62]3 years ago
3 0

I assume you're supposed to establish the identity,

cos(A) cos(2A) cos(4A) = 1/8 sin(8A) / sin(A)

Recall the double angle identity for sine:

sin(2<em>x</em>) = 2 sin(<em>x</em>) cos(<em>x</em>)

Then you have

sin(8A) = 2 sin(4A) cos(4A)

sin(8A) = 4 sin(2A) cos(2A) cos(4A)

sin(8A) = 8 sin(A) cos(A) cos(2A) cos(4A)

==>   sin(8A)/(8 sin(A)) = cos(A) cos(2A) cos(4A)

as required.

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Solve for y.<br> 7y - 6y - 10 = 13
Orlov [11]

Answer:

y= 23

Step-by-step explanation:

Solve for  (y )

by simplifying both sides of the equation, then isolating the variable.

7y - 6y - 10 = 13

7 0
3 years ago
What is the surface area of cone below Diameter AB=21 and distance from B to C =36
Vesnalui [34]

Answer:

1533.88261311522

Step-by-step explanation:

<em>Let r be the radius of the (base/circle)</em>

<em>and  L be the slant height of the cone</em>

<em>Formula ………………………………………………………………………………………………………</em>

The surface area of a cone = the (curved/lateral) surface area +  the base

                                             =\pi r^{2}\ \ \ +\ \ \ \pi Lr

=========================================

r=\frac{21}{2} =10.5

L = BC = 36

\text{surface area} =\pi \left( 10.5\right)^{2}  +\pi \times 36\times \left( 10.5\right)

                   =346.360590058275 + 1187.52202305694

                   =1533.88261311522

6 0
2 years ago
The first three terms of a sequence are given. Round to the nearest thousandth (if necessary).
BabaBlast [244]

Step-by-step explanation:

the introduction of a fraction tells us that we are dealing with multiplications, and therefore a geometric sequence (where every new term is created by multiplying the previous term by a constant factor, the ratio r).

I think your teacher made a mistake, or you made one when typing the question in here.

there is no factor r that creates

15×r = 9

and

9×r = 5/27

it would mean that

15 × r² = 5/27

r² = 5/27 / 15 = 5/27 × 1/15 = 5/405 = 1/81

r = 1/9

but 15 × 1/9 = 5 × 1/3 = 5/3 is NOT 9

and 9 × 1/9 = 9/9 = 1 is NOT 5/27

so, this can't be right.

on the other hand

15 × r = 9

r = 9/15 = 3/5

and then

9 × 3/5 = 27/5

so, either the sequence should have been

15, 5/3, 5/27

or (and I suspect this to be true)

15, 9, 27/5

under that assumption we have

s1 = 15

r = 3/5

sn = sn-1 × r = s1 × r^(n-1) = 15 × (3/5)^(n-1)

s10 = 15 × (3/5)⁹ = 15 × 19683/1953125 =

= 3 × 19683/390625 = 59049/390625 =

= 0.15116544 ≈ 0.151

6 0
2 years ago
This is for middle school 9th grade please help me :)
saw5 [17]

Answer:

1 because it goes up 3 over 3      3/3=1

Step-by-step explanation:

4 0
3 years ago
Evaluate the radical. 125−−−√3
VikaD [51]

Answer:

Answer should be 5

Step-by-step explanation:

3 0
3 years ago
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