Answer this please, thank you !
1 answer:
Answer:
m∠ADC=55°
Step-by-step explanation:
step 1
Find the value of x
we know that
m∠CDE+m∠EDF=180° ----> by supplementary angles (form a linear pair)
substitute the given values
solve for x
step 2
Find the measure of angle ∠ADC
we know that
m∠ADC=m∠EDF ----> by vertical angles
m∠EDF=(x-7)°
substitute the value of x
m∠EDF=(62-7)°=55°
therefore
m∠ADC=55°
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Question 14, Part (i)
Focus on quadrilateral ABCD. The interior angles add to 360 (this is true for any quadrilateral), so,
A+B+C+D = 360
A+90+C+90 = 360
A+C+180 = 360
A+C = 360-180
A+C = 180
Since angles A and C add to 180, this shows they are supplementary. This is the same as saying angles 2 and 3 are supplementary.
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Question 14, Part (ii)
Let
x = measure of angle 1
y = measure of angle 2
z = measure of angle 3
Back in part (i) above, we showed that y + z = 180
Note that angles 1 and 2 are adjacent to form a straight line, so we can say
x+y = 180
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We have the two equations x+y = 180 and y+z = 180 to form this system of equations
Which is really the same as this system
The 0s help align the y terms up. Subtracting straight down leads to the equation x-z = 0 and we can solve to get x = z. Therefore showing that angle 1 and angle 3 are congruent. We could also use the substitution rule to end up with x = z as well.