Question

plz solve them....and no spamming plz​

Answer 1

Answer:

12.we know that sum of area of triangle is 180°

a+B+c=180°

B+c=180°-a

divide By tan and 2 on both side

tan(b+c/2)=tan(180°/2-a/2)

tan(b+c/2)=tan(90°-a/2)

tan(b+c)2)=Cot a/2. {tan(90-a/2 =cot}

Answer 2

Step-by-step explanation:

10) y sin²63°+y sin²27°/4cos²17°+4 cos²73°) = -1/2

=> ysin² 63°+ysin²(90-63°)/4cos²17°+4cos²(90-17°) = -1/2

=> ysin²63°+ycos²63°/4cos²17°+4sin²17° = -1/2

=> y(sin²63°+cos²63°)/4(cos²17°+sin²17°) = -1/2

=> y/4 = -1/2 [ sin²A + cos²A = 1 ]

=> 2y = -4. [sin (90-A) = cos A ]

=> y = -2