Take note that they spent $18 afterwards having $28 on the card so they're spending money off the card so...
x-18=28
would be the equation for this and to solve do the following.
First add 18 to both sides making the equation.
x=46
Just use the Pythagorean Theorem
(9 +x)^2 = 15^2 + x^2
x^2 + 18x + 81 = 225 + x^2
18x = 144
x = 8
So the three sides of the triangle are
15, 8 and 17
Answer:
213 or 213.68 or 214
Step-by-step explanation:
5342 divided by 25 it is 213.68 rounded it would be 214 but its only asking for the full boxes so it may be 213
Write the left side of the given expression as N/D, where
N = sinA - sin3A + sin5A - sin7A
D = cosA - cos3A - cos5A + cos7A
Therefore we want to show that N/D = cot2A.
We shall use these identities:
sin x - sin y = 2cos((x+y)/2)*sin((x-y)/2)
cos x - cos y = -2sin((x+y)/2)*sin((x-y)2)
N = -(sin7A - sinA) + sin5A - sin3A
= -2cos4A*sin3A + 2cos4A*sinA
= 2cos4A(sinA - sin3A)
= 2cos4A*2cos(2A)sin(-A)
= -4cos4A*cos2A*sinA
D = cos7A + cosA - (cos5A + cos3A)
= 2cos4A*cos3A - 2cos4A*cosA
= 2cos4A(cos3A - cosA)
= 2cos4A*(-2)sin2A*sinA
= -4cos4A*sin2A*sinA
Therefore
N/D = [-4cos4A*cos2A*sinA]/[-4cos4A*sin2A*sinA]
= cos2A/sin2A
= cot2A
This verifies the identity.
