Answer:
Its letter A the first answer
1. Angles ADC and CDB are supplementary, thus
m∠ADC+m∠CDB=180°.
Since m∠ADC=115°, you have that m∠CDB=180°-115°=65°.
2. Triangle BCD is isosceles triangle, because it has two congruent sides CB and CD. The base of this triangle is segment BD. Angles that are adjacent to the base of isosceles triangle are congruent, then
m∠CDB=m∠CBD=65°.
The sum of the measures of interior angles of triangle is 180°, therefore,
m∠CDB+m∠CBD+m∠BCD=180° and
m∠BCD=180°-65°-65°=50°.
3. Triangle ABC is isosceles, with base BC. Then
m∠ABC=m∠ACB.
From the previous you have that m∠ABC=65° (angle ABC is exactly angle CBD). So
m∠ACB=65°.
4. Angles BCD and DCA together form angle ACB. This gives you
m∠ACB=m∠ACD+m∠BCD,
m∠ACD=65°-50°=15°.
Answer: 15°.
Hello aysha123994 i am sure that it could be 17. if i am wrong forgive me
Answer:
Step-by-step explanation:
Answer:
Arc length ![=\int_0^{\pi} \sqrt{1+[(4.5sin(4.5x))]^2}\ dx](https://tex.z-dn.net/?f=%3D%5Cint_0%5E%7B%5Cpi%7D%20%5Csqrt%7B1%2B%5B%284.5sin%284.5x%29%29%5D%5E2%7D%5C%20dx)
Arc length 
Step-by-step explanation:
The arc length of the curve is given by ![\int_a^b \sqrt{1+[f'(x)]^2}\ dx](https://tex.z-dn.net/?f=%5Cint_a%5Eb%20%5Csqrt%7B1%2B%5Bf%27%28x%29%5D%5E2%7D%5C%20dx)
Here, 
interval ![[0, \pi]](https://tex.z-dn.net/?f=%5B0%2C%20%5Cpi%5D)
Now, 
![f'(x)=\frac{\mathrm{d} }{\mathrm{d} x}\left ( [-cos(t)]_0^{4.5x} \right )](https://tex.z-dn.net/?f=f%27%28x%29%3D%5Cfrac%7B%5Cmathrm%7Bd%7D%20%7D%7B%5Cmathrm%7Bd%7D%20x%7D%5Cleft%20%28%20%5B-cos%28t%29%5D_0%5E%7B4.5x%7D%20%5Cright%20%29)
Now, the arc length is ![\int_0^{\pi} \sqrt{1+[f'(x)]^2}\ dx](https://tex.z-dn.net/?f=%5Cint_0%5E%7B%5Cpi%7D%20%5Csqrt%7B1%2B%5Bf%27%28x%29%5D%5E2%7D%5C%20dx)
![\int_0^{\pi} \sqrt{1+[(4.5sin(4.5x))]^2}\ dx](https://tex.z-dn.net/?f=%5Cint_0%5E%7B%5Cpi%7D%20%5Csqrt%7B1%2B%5B%284.5sin%284.5x%29%29%5D%5E2%7D%5C%20dx)
After solving, Arc length
