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## Answers

sinA+sinB=2sin(a+b)/2.cos(a-b)/2

2sin(50+10)/2.cos(50-10)/2+2sin(40+20)/2.cos(40-20)/2

2sin60/2 cos40/2+2sin60/2.cos20/2

2sin30cos20+2sin30cos10

2*1/2 cos20 + 2*1/2 cos10

cos20+cos10

cosA+cosB=2cos(a+b)/2.cos(a-b)/2

2cos(20+10)/2.cos(20-10)/2]

2cos30/2.cos10/2

2cos15.cos5

2sin(90-15)=2sin75.cos5

2sin(45+30).cos5

2(sin45cos30+cos45.sin30)cos5

2(1/√2*√3/2+1/√2.1/2)cos5

2/√2(√3/2+1/2)cos5

√2(√3+1)/2 cos5

(√3+1)/√2 cos 5

cos 5 is tends to 1 so take cos 5 = 1

because cos is a decrasing function so value of cos 5 is 0.99872something ≈1

(√3+1)/√2 *1

ans will be (√3+1)/√2