Yes I need points so I’m commenting random stuff lolololo
Answer:
Step 2: 20x = 80 + 10x
Step-by-step explanation:
Step 1: 20x - 10 = 80 + 10x
Add 10 to each side
20x - 10+10 = 80+10 + 10x
20x = 90 + 10x
Step 2: 20x = 80 + 10x This has the first error
Step 3: 10x = 80
Step 4: x= 8
Let's work on the left side first. And remember that
the<u> tangent</u> is the same as <u>sin/cos</u>.
sin(a) cos(a) tan(a)
Substitute for the tangent:
[ sin(a) cos(a) ] [ sin(a)/cos(a) ]
Cancel the cos(a) from the top and bottom, and you're left with
[ sin(a) ] . . . . . [ sin(a) ] which is [ <u>sin²(a)</u> ] That's the <u>left side</u>.
Now, work on the right side:
[ 1 - cos(a) ] [ 1 + cos(a) ]
Multiply that all out, using FOIL:
[ 1 + cos(a) - cos(a) - cos²(a) ]
= [ <u>1 - cos²(a)</u> ] That's the <u>right side</u>.
Do you remember that for any angle, sin²(b) + cos²(b) = 1 ?
Subtract cos²(b) from each side, and you have sin²(b) = 1 - cos²(b) for any angle.
So, on the <u>right side</u>, you could write [ <u>sin²(a)</u> ] .
Now look back about 9 lines, and compare that to the result we got for the <u>left side</u> .
They look quite similar. In fact, they're identical. And so the identity is proven.
Whew !
ANSWER:
[i] 4 × 10.56 = 42.2
[ii] 5 × 0.432 = 2.16 (not 2.18)
So, <u>Correct choice</u> - [B]
THis is a hexagon and total of internal angles = 720 degrees
so x is 720 - 112 - 133 - 128 - 100 - 120 = 127 degrees answer
