Answer:
- 0.944

Step-by-step explanation:
We know that,
cos 3A = 4 cos³A - 3 cos A (formula)

So,
If cos A = 0.4,

cos 3A = 4 cos³A - 3 cos A
cos 3A = 4 × (0.4)³ - 3 × (0.4)
cos 3A = 4 × 0.064 - 1.2
cos 3A = - 0.944

Hope it helps ⚜

3 0

2 years ago

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In ΔCDE, the measure of ∠E=90°, the measure of ∠C=70°, and DE = 12 feet. Find the length of CD to the nearest tenth of a foot

Radda [10]

Answer:

$CD = 4.4ft$

Step-by-step explanation:

Given

$DE = 12$

$\angle C = 70^\circ$

Required

Find CD

This question is represented with the attached triangle

To solve CD, we make use of tan formula.

$tan(70) = \frac{DE}{CD}$

Substitute 12 for DE

$tan(70) = \frac{12}{CD}$

Make CD the subject

$CD = \frac{12}{tan(70)}$

$CD = \frac{12}{2.7475}$

$CD = 4.4ft$ --- approximated

6 0

2 years ago

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Find the slope of the treadmill shown to the right

Nata [24]

There is no treadmill

6 0

3 years ago