Since the sine and cosine functions are cofunctions, they are complementary. The format for this is that sinx=cos(90-x). This works for secant and cosecant and tangent and cotangent. So, sin25°=cos65°.
        
             
        
        
        
Answer:
The measure of the largest angle is 72º.
Step-by-step explanation:
We will first solve for x. We know that the sum of the interior angles of a triangle is 180º, so 15x + 21x + 24x is equal to 180º. This means that 60x = 180º, so x = 3º. The largest angle is 24x, which is 72º.
 
        
             
        
        
        
Subtract the two equation from each other
-3x-7y=-66
-10x-7y=-24
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7x =-42
x=-6
by substituting in equation 1
(-3)(-6)-7y=-66
18-7y=-66
-7y=-84
y=12
so to check we substitute in the first equation
(-3*-6)-(7*12)=-66
18-84=-66
-66=-66
we check the second equations
-10(-6)-7(12)=-24
60-84=-24
-24=-24
        
             
        
        
        
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